2056 running L-jet

Car starts and has a noticeable miss when cold, popping while holding throttle at 2k.

Once warmed up it seems to flatten out and run a bit smother.

However under acceleration it just doesn't feel like it has much power and it feels like it could be running on 3 cylinders.

Spark on all cylinders
All 4 Injectors are spraying with good patterns
Fuel filter was changed at the beginning of the summer
Fuel pressure was 33 @ idle and 35 under acceleration and 39 under hard acceleration when checked the other month.

I put in a new fuel pump relay due tot he old one giving me issues. The only thing left that I can think of is does the wiring harness have a broken wire in it that makes partial contact at times, but don't know if that would even create symptoms like this.

Any ideas of where or what else to look for?

Vacuum leaks. Points (if any). Timing advance/retard sticking. Points signal to FI has poor connection. And more...

--DD

You can narrow your search for the problem cylinder by first pulling loose all the plug wires off the distributor cap and lay them loosely in place. Then start the motor and one by one, pull each plug wire off with a pair of insulated pliers. When you pull the plug wire which does not effect the speed of the motor, you have found the cylinder with the issues.

Where is the popping coming from? Intake or exhaust?

No vacuum leaks
Distributor has pertronix and was just dismantled and cleaned and relubed

Popping referring to it missing while cold not a and back fire or raw gas igniting