94 lt1 t56.
Bought my camaro about 6 months ago. Ran beautifully!! Untill about 2 months ago. Started to have some power issues but wasn too bad. Gradually day by day it got worse. Here's the problems.
1. No power. When u hit the gas any harder then babying it it bogs down and makes a ratling noise from the motor. And when u REALLY gas it it looses all power and backfires.

2. To start it you have to turn the key to "on" position, let the fuel pump kick on and then turn it off and repeat. Then it starts up fine. If u only turn the key to on once and turn the motor over it cranks and cranks and will eventually start but then run crappy untill it smooths out and idles at 1500rpm and then slowly comes down to 900rpms.

3. When its idling it sounds and runs great. Even if you rev the motor to 5500rpms its still good. Only when u are in gear does it run like crap and sound like crap. Trans and clutch are almost brand new and have no problems.

4. I can get I up to even highway speeds (after awhile) and when I'm just cruising keeping the speed limit it feels very jerky. Like the motor is pulsing. And even a small incline forces me to downshift because if I just keep it in say 5th doing 50- 55 mph I loose a lot of speed.

Just replaced the fuel pump today. Made no diference. No check engine lights are on. Stock plugs and wires. Moroso intake (however air inlet elbow is tight but if u take it off while motor is running car stalls out. Someone told me that was a good thing????)
Fuel pressure guage read "0 psi" when motor off and key on. "36 psi" when motor running. "41 psi" when motor revved to 6000rpm. Obd1 read "no codes pulled".
Sorry this is so long but someone please help. Thank you.

 

Do you still have the catalytic converter in place? If so, sounds like it may be plugged up.

The sluggish start without priming the fuel pump more than once is typically failure of the check valve in the pump. Does the fuel pressure drop rapidly after the pump runs for 2 seconds and shuts off?

How did you pull the codes?

 

I went to a shop and paid 85 bucks to have the obd1 read. And no codes came up. The fuel pump is brand new just installed it today. Works and sounds strong. The cat is removed its straght piped. Still no clue tho..

 

Sounds very obvious I know.....have you replaced the fuel filter? If it's starting to get plugged up you could be starving under load. Just a thought. I apologize if you have already long since tried that. Sometimes the obvious is the answer. Hopefully it is.....because that is el cheapo and easy