1976 2.0 D-Jet Hesitation from about 3700-3900 RPMs, updated 1st post Resolved Options

[gunny]

My motor runs good from Idle to ~3500-3600 RPms then it hesitates (loss of power) like the fuel or fire is disrupted unless I pump the peddle. This lasts untill ~3900-4000 RPMs where it continues to accelerate. This happens in all gears accept 1st (guessing there is not enough back preasure in 1st). It doesn't just happens at full throttle it also happens if I try to cruse at that RPM range. (IMG:style_emoticons/default/sad.gif)

I have replaced and adjusted the TPS and the symptom has not changed.

What is the ECU doing at this RPM range that could cause this. (IMG:style_emoticons/default/WTF.gif) I think the ECU doesn't like some input it is getting at that time or could it be the distributor?

Looking for suggestions.

Most of the emissions stuff is removed.


UPDATE:

Issue fixed after many months of analysis.
Problem was car was running too lean A/F would spike around 3700 RPMs to 17:1 (bad). A\F was below 13.5 :1 above and below that RPM range.

What I went through. 1st I checked everything anyone suggested. Then I built a complete 2nd distributor from parts (no change to problem), Diffrent TPS (no change to problem), diffrent ECU (no change to problem), New plug wires, plugs, coil, had injectors cleaned and flow tested (no change to problem), addded wideband A/F meter and noticed that the A/F mixture was too lean. bought a calibrated MPS (no change to problem). Purchased an LCR meter and went to work adjusting my origional MPS. Started with numbers from MPS writeup but was still to lean with hesitation. Made some adjustments based on what I was seeing on the A/F meter and Vacuum gage and now it runs great. I'm running as high as 13:1 but spend most of the time between 12.2:1 and 12.8:1 except during WOT when it drops to about 11:1. The car runs better than it ever has during the 1 year I've owned it.

I think that if you have a 75-76 car which was designed with all of the emisions crap on it and you have taken all of it off like I do you are most likely running lean. The motor now needs more fuel. Just getting an MPS that is calibrated to the factory numbers didn't fix my problem.

The bad news is that it took me almost a year to fix it and I purchased a lot of parts that I didn't need.

The good news is that I have a great running car and a set of good spare parts (ECU, MPS, Distributor, TPS)