Im putting a 350 into my car within the next 3 months but I need to get a few things figured out first and the main one would be my (misfire) problem. I don't know exactly whats happening. My dad (mechanic of 20+ years) says I need new idle air control motors.
Watch the video please, what happens is when I push the throttle all the way down (moving or park), it goes for a split second, stops, then continues like normal. If I push it halfway down while moving it loses power like its cutting out and then gains it back slowly (after 5 seconds or so).

The last rev really shows it good.

 

Dont worry about the IAC's. They only control idle speed. Your problem is giving it throttle and reving the engine. You probably have either a fuel concern or an ignition concern or both. Need to start by checking fuel pressure and the spray of the injectors. Timing could be off. Need to check for any codes. Could be a base engine concern. Have you replaced any parts yet? I imagine one of the crossfire guys on the board will chime in and help with any problem you're having.

 

Replaced spark plugs and fuel filter. Today I was going 5mph, pressed the gas down and it gave a big clunk and almost died.

My engine needs piston rings which is the reason behind the rebuild of the 350.

 

Check your fuel pressure. It could be a fuel pump. I am having similar issues and I suspect low fuel pressure.
This is my thread. I will be checking fuel pressure tomorrow.
https://www.thirdgen.org/forums/tbi/...ml#post5444131