420a idle and acceleration issue

[deepblue628]

Hello, I have a black eclipse with a 420a that will not accelerate under load. It starts and idles rough. It will rev fine but not under load, easing the gas can rev it to redline. Thinking it was a fuel issue I have replaced the fuel pump, regulator, and injectors. System shows (45ish Psi).
Issue still existed. Next I replaced the throttle position sensor, map sensor, crank sensor, cam sensor, o2 sensor, and coil pack. Testing after each it still had issue. I checked plugs and all have good spark. Used noid lights to confirm pulse to injectors. Still had issue but we replaced the PCM regardless. A local shop tested the compression and it is good, the timing is also spot-on. Thinking the exhaust may be clogged we unhooked it at header and still had issue. Also uncooked the intake air temp sensor and no change. The PCV was also unhooked with no change (each was unhooked with everything else intact). Flooring the car from idle makes it backfire and it sounds as though it is underwater. But easing the gas the engine is smooth all the way to limiter.
All fluids are fine and normal color. This issue started when my brother was going 60ish under minimal load. He said it just shut off and has been like this since. Please shoot me ideas as I don’t know what else to test.

 

[GofaST4life]

I'm not a 420a guy, but since you've pretty replaced everything, I have two questions.

1. Have you checked your ECU?

2. Are there any CEL codes?

 

[deepblue628]

The only code was for multiple misfire. As mentioned we did replace the ECU and there was no change. Also pulled valve cover and there is no broken valve springs or anything else broken in the head

 

[smokedatalon]

i would try map sensor or maybe ignition coil just some ideas..

 

[fiveeauxfo13]

Been having same issues, done most tests ve done, find out i got a f.p.r. vacuum leak coming from the dome part of it!!!