Yes punk, go hide. You've been out-classed here.

you know what im man enough to say I was wrong you are right I dont know what I talk about.. and the iac can't do anything after idle and ill call merc tomorrow and tell them that they are wrong and im a punk that knows nothing about fuel injection and to please take my certs beacuse I know nothing and then ill call all my customers for the last two years that I built there motors and drives and tell them I know nothing and that they are sh*t out of luck ......because there fountains, actives and sonics wont
live and im a punk... and know nothing cool

ED try to have a nice day!

you know if nothing else you are fun ..... .......... thanks

More proof I'm right about your character.

I hope you work in the back-room where you never have to come face-to-face with the customers.

You're welcome. Now I'm going to bed and dream about engines cutting out at 2,000 RPM and trouble codes and bad fuel and shorted out ignition systems and it's all studstud's fault!

This is a longshot, maybe even way out there, <US1 ducking down low> but a friend had a very similar condition this summer with one of his 454 mpi's. that went on for a few days. Ran fine, then for no reason while running it would cut in and out. Back to idle, all is fine. Back into the throttle, start cutting out again. Finally dead. Turned out the main wire harness plug came loose at the rear of the motor. It was still connected, but not making contact. The cutting in and out must have been while the plug was working it's way out.

Did anybody mention the IAC motor yet???? Sorry couldn't resist...

The coils are seemingly a common failure just swich them on your motors see if the problem moves, as mentioned above check wiring, power grounds. I actually had a similar problem and it ended up being a bad connection for the main power supply under the dash to my fuse panel, good luck...

Just a shot in the dark here, but my father had this happen years ago on one of his 454 mag/efi's. It turned out to be bad batch of gas and a plugged fuel filter. Hope it might be something that simple.

I've seen a bad ground connection, wiring harness, connction, etc be the culprit more then once, after the owner has thrown $$$ away replacing many parts with symptons you've described.

Disclaimer: I'm not a mechanic nor surveyor but rather just a dumb azz who's " been there done that " with issues such as yours..