Z28 loss of power

I have a 1996 Z28 with 5.7L and 6 speed manual. Just got the car and noticed it was missing catalytic convertors. So I had the corvette shop next to me install them. They also replaced the clutch which was bad. After this repair I could not get any power/acceleration out of the car. It does not want to move like something is choking it. It also happens in higher gears with higher RPM. But in idle the car sounds awesome. I took it back they said that the temperature sensor to the computer was disconnected so they got a new sensor. But the car still has no power. They also checked the fuel pressure and it was fine. The check engine light keeps coming back after reset as well. What could be wrong?

What they should be checking is their catalytic converter work. It sounds like exhaust restriction. I’d also say that the fuel pressure may be suspect, but if this condition is new since the work then revisiting the cat work would be the first place to go.

First step is scan the car for codes. AutoZone will do this free.

There’s not enough info to make much of a guess here but a MAF problem is not out of the question.

Question though. Did this car run at least well before the clutch job? If so, maybe the clutch job was not done properly and it’s slipping.
Set the park brake and hold the foot brake. Put the transmission in 3rd gear and rev the engine while releasing the clutch pedal. The engine should die abruptly. If not, back to the drawing board on the clutch.

Whats an MAF?
The car was running very well ( minus the clutch ) before the CAT work.
The clutch is pretty good now. Before it was chattering and I could hardly drive the car. Yes the car dies in park and 3rd gear.
Could it be that the ECU needs adjusting or maybe they had replaced it? After installing the CATs shouldn’t the car be reprogrammed for fuel/air mixture?
As for scan they have a hand scanner that they plug in under the dash. Is that enough or would they need a more better unit to also measure the exhaust pipe?

They just changed an O2 sensor and now it appears to be running well.