After thinking this was fixed, today my car (91 740 turbo 5 speed) acted up again. It will rev okay in first gear to 5k then in second gear it will not rev very well, 3rd gear it revved better but would choke and hesitate around 3500 rpms. This is similar but different from what it was doing before.

My exhaust has started making a lot of noise after I did my turbo hoses and when it chokes out the exhaust starts making more noise and knocking and banging sounds. It sounds like the exhaust leaks are coming from the catalytic converter area (i.e. under the car and not behind the car).

Could a clogging cat cause these sorts of problems?

I do not think its a fuel delivery issue as its a new FPR, new RI suppression relay the pumps both sound okay, there is a new full tank of gas so I don't think its a feeder tube and it was driving great last night and the throttle response is fine until it chokes and it feels like something is clogged.

I have also done an ignition coil and the plugs and cap and rotor are also new.

My check engine light does not come on with any of this stuff so I would be inclined to think it’s not electrical or a sensor.

Could a sensor cause this problem, if so which one?

I will be under the car tomorrow to see exactly where the exhaust is leaking.