Trying to get some ideas on an issue my car has. I recently got this 86 NA Automatic trans. It had a terrible ATF leak which I discovered was the result of a missing torque converter seal in the bell housing. Previous owner had done some trans work and reinstalled it without the seal. The engine ran great before I took the AT out and put it back in. After I replaced the trans and got everything plugged back together, the engine starts and idles fine, but it cuts out at 3000 rpm or so. It basically revs to 3K, cuts out and picks back up after dropping below 3K. BTW - I can actually drive the car and it runs and works just fine below 3K.

I'm concerned that I am overlooking something really obvious that is directly related to the transmission R&R. Plugged wires together incorrectly, created a vacuum leak or a faulty connection somewhere, IDK.

I have changed the fuel filter - thinking I clogged it by stirring up sediment during the up and down jacking. No change. Also, I don't hear any strange noises from the fuel pump.

I tried disconnecting the MAF. Disconnecting it when the car is off prevents it from starting. Disconnecting while the engine is idling and it stalls as soon as I step on the gas. So it seems that the MAF is working properly.

Today I found a thread and video that suggests the CAS could be dirty or corroded so I will check that tonight.

What else should I be checking?

Thanks in advance!