I have a 1996 Chev with the 5.7L Vortec (that was rebuilt a little over a year ago) and its hard to start after it sitting for about two hours or longer when its warm. It starts fine when cold and right after i shut it off when hot. It was starting fine until now, but once its running its perfect just harder to start. Had someone with a scanner check it out and he said he couldn't find anything wrong and theirs no codes other than having no rear o2 sensors cause i got my cats cut out thinking that this was my problem cause the truck doesn't seem to have as much power as it should, and it didnt change anything other than give me an engine light now.

Whats new on the truck when rebuilt last year: ​​​rotor and cap, fuel pump, oil pressure switch/sending unit, knock sensor, spark plugs, new spark plug wires, bigger battery (1000CCA)
What i just changed/done this year: coolant temp sensor, TPS, new MFI injectors with new regulator, and filter. I cleaned the MAF and throttle body. New used ICM and coil.

I have no idea what I should try next and everyone I talk to doesn't either...any help is appreciated

 

what type of fuel injection set up? Fuel leak down into the cylinders will cause a hart start after a hot soak. put a pressure gauge on the fuel rail and prime the system; monitor for a pressure drop after shutting off the engine.

 

It's has the updated version of the OEM injectors, the MFI injectors that don't have the poppet valve on end. The injectors are brand new so they shouldn't leak...before I put them in I did a pressure test and the old ones were good the pressure went up to 65 psi and held it there for a while. I could double check again just to make sure though 🤷