Installed engine, now runs like SH*T

[anarchy04]

My friend just put the engine back in has 92 DOHC base modle Talon and now it backfires into the intake and won't idle and revs kinda slow, floor it and it hesitates then has trouble hitting 6500 rpms then let off and it will stay up at 6500 for a second then drop back down, like a delayed response, once you rev it up some it doesn't misfire any more, put a new timing belt on and it is all on the marks, checked the plugs, they were fine, pumped the 4 year old gas out and put in a couple of gallons of new gas and some of that water remover stuff, it has seemed to run a little better every time we do something but still runs horrible. When you hold the gas down at a certain point like a quarter throttle or something it will spit and sputter for a little while then all of a sudden like "grab" and rev up quick. All this is in park too.

 

[jwahl425]

is your check engine light on? if so I would get the code from it, if not I would say you have a bad ECU, i mean that is the onlt thing that I can think of that would create such a bad throttle response. or it could be your ISCM (Idle speed control motor) is the engine the same and you just fixed something or is it a diff. engine? did you have any rev related problems before engine was replaced?