1998 Chevy 5.7 k1500 misfire poor idle

[Tate22]

Hello I have a 1998 Chevy k1500 5.7, I recently put in a new 5.7 crate engine .40 over. Swapped all the old parts over and got it running and timed. Ever since we got it timed correctly it almost feels like a misfire past about 30% throttle. Very low in power and has a very rough idle almost dying sometimes. I’ve checked spark, air and fuel. Only problem is fuel pressure is a little below 60 during idle and pre ignition. There are no codes at all. Voltage to fuel pump relay is as it should be. I’ve replaced spider injection unit, fuel pump, cap, rotor, wires, plugs, maf sensor, map sensor, fuel pump relay. Kinda stuck at this point been wanting to take it to a dealership but don’t want to spend an arm and a leg for diagnosis. Any suggestions? Also have checked grounds and wires around injection unit. Thanks! 

[CamGTP]

That fuel pressure sounds just fine, it should only need around 55-61psi on that year.

 

What do your fuel trims look like?

 

Technically you can't just plop a bored engine in and have it run perfect on a stock tune.

[Tate22]

Not sure would have to look tomorrow.

That is mostly my concern, Haven’t really heard or read anything about the stock ecu not being able to handle a bored block. I do need to get ckp variation learn done because I have replaced crank sensor and cam sensor as well.