I can say I agree with the other poster, that you have change “too many” parts but hey, it help rule out things and keeps you entertained!

150 psi would be better. The 120 psi is a little low and probably proves high mileage but it is even, so it will run even, IMHO. 90 psi to 105 psi can be dying cylinders, IMO. This also depend on the procedure used to test compression the cylinders and then the valves. Some people forget to open the throttle wide open too.

A plugged muffler can cause slow power up and the old cat converter might have helped that along. Was the old cat converter empty of its goodies?

Interesting that the vacuum hose comes off but which end? The port fitting going into the manifold might plug up with carbon and oil deposits. I think it unscrews for inspection and for a good snug fit to the hose. Excessive blow by can be from a plugged muffler and add to those conditions too.

The flooding cannot happen by working the throttle with the foot. The foot only adds air. It sounds like you are compensating for an overly rich running engine or one that cannot pass enough air. I feel like I am vacillating!

Double check the ECT at the ECU as there may be some bad wiring or connections.

The engine will pull lousy like being choked but for this car that might be caused by a bad injector and found by one plug worse than the all the others. A leaky cold start injector will flood the entire engine. Rare for injectors to be a problem but if you need entertainment again, I think you could just unplug it, to see “If” the ECU is turning it on. I never had to try that idea myself.

Are you getting a check engine light for a rich condition? Check the codes just in case the dash bulb is out or inoperative from the ECU, if that is possible and still have it work from the key on before starting mode.

I guess I will go run around the house a couple of times for some more entertainment, as I cannot do anything else to your car.
Good Luck ... Phil