1976 FI 2.0 all stock.
Put it away for the winter, now it stutters like crazy under a load at 3,800 to 4,000 rpm. It stutters and bucks so much that it won't pull itself out of the trouble range. Tachometer stays steady. If I shift to a lower or higher rpm gear, it runs great.

Checked compression, dwell, timing, valve adjustment, spark at plugs, coil resistance...All within range.

Distributor cap, rotor, condensor, and points all look good and have less than 400 miles on them from last year. I can't seem to find any vacuum leaks, but will be replacing all vacuum lines later this week. New plugs last year also...They are still gapped properly, but the 1 through 3 plugs have some dry carbon buildup that is not present on cylinder #4 plug.

Haven't yet checked fuel pressure...Can't seem to find a tap point on the rails.
Haven't changed the fuel filter yet since the last one seems to have trapped itself under the tank...Not an issue, I'll be replacing the lines with stainless from Tangerine when they arrive. Not sure how it can be fuel related since the car runs great outside of this rpm range. Seems to me that it is more likely to be electrical.

Anybody ever run into this issue? Any suggestions would be appreciated.
Axel

Your tps board has probably worn or it needs to be adjusted.

Thanks for the response. I thought about the TPS board, but if I run wide open, it runs great up to the 3,800 rpm point, then starts bucking. Since the throttle position doesn't change during this test, I wouldn't expect the TPS board to be the issue. Maybe I am misunderstanding how the board works?

The traces get worn where they sit at one spot. Like at cruise.
Unplug it. If the stumble goes away, you need a new board.

Actually, that was the first thing I did when I encountered the stuttering last week.
Unplugging the TPS didn't make any noticeable difference.

Could it be a sticky mechanical advance on the distributor? Although my old Volvo stumbled like that when the TPS got oxidized. I wiped it clean with rubbing alcohol, and it would be good for a while.

I had the same problem. Tried everything. fuel lines, vaccuum lines, gaskets, dizzy, points, injectors, plugs, wires, tps, fuses, checked mps, ect. Seemed to go away with a different (used) coil. Mine was origional to the car.

I thought about the centrifugal advance on the distributor also. I was really hoping somebody had an easier answer. I've never taken apart the distributor to clean it. Anybody ever cleaned the weights in the distributor? How difficult is it to get to?

Mine was replaced approximately 4 years ago. Tested fine, but I fortunately have a spare that I can try tomorrow. Thanks for the suggestion.

I have the same thing on my 76 2.0 Djet. I have tried everything. When it stumbles at 3800 rpms if you pump the gas peddle does it go past the bucking and run great above 4000 rpms? Mine seems to be a something with the firing of the fuel injectors

Pumping the pedal doesn't do anything, but if I downshift it runs great over the 4,000 rpm point.

Same symptoms as mine except some days it would be fine. I cleaned and replaced everything from the tank to the injectors but it wasn't a fuel issue. I'm 99% sure it was a spark issue. Old coil just wasn't putting out enough juice. Rebuilding the dizzy didn't help. I still plan to buy a new coil but switching out the old one made the car run much better. Good luck guys!

All origional '71 d-jet

How do the points look. I had the same problem with my 75. New point, condenser and timing did the trick for me.

Also make sure the distributor is buttoned down

Points look clean, dwell is at 50 degrees.
Distributor cap, rotor, points, plugs, coil, and condenser were all replaced approximately 400 miles ago. I have another full tune-up set including new wires, so I'll start replacing part by part to see if it makes any difference.

When you throttle the engine what does your tachometer do. Mine use to be very bouncy and had the same problem of bucking at that RPM, until I tuned it, try backing down a little on the dwell the range is 44 to 50 degrees.

Tach is very steady...No bouncing at all.

do you have another set of trigger points? I have had a similar miss at somewhere around 32-3500 rpm...new trigger points fixed it...

Took apart and cleaned distributor. Replaced coil, condensor, trigger points, ignition points, cap, and rotor. Replaced all vacuum hoses. Adjusted dwell and timing. No change to the stuttering/bucking. Any other thoughts?

I had this exact same issue in my 74 2.0 for 10 years. Numerous mechanics looked at it and were unable to figure out what was going on. I finally took it down to Brad Mayeur and he tried unplugging Temp Sensor #2. For some reason that completely resolved the bucking at 4k rpm. It's worth noting that I have a Petronix installed, so it definitely wasn't the points/condenser.

Thanks, I'll give it a shot.

Thanks to all for your input. After changing everything out without it having any effect, I checked the wiring for both temperature sensors. Nothing seemed out of place, but after checking these wires, the stuttering and bucking seem to have gone away.

Well that's great. If it comes back, you now know where to look.

Which sensor is #2? I have the same issue.

I don't know which it was. I moved both wires a while I was examining them. I couldn't find any problems with either one, but the physical manipulation of them seemed to fix the stuttering. I must have a short in one of them.

temp sensor # 2 is the head temp. Only has one wire. #1 is the intake air temp. The one in the plenum, next to the tps on a 2.0L. It has two wires. The thermo tine switch, which senses ambient air temp, has one wire. It tells the ecu if its cold enough to turn on the cold start valve. Its mounted below the plenum on the bracket that bolts the plenum to the case. Its on the passenger side.