That much pressure suggests to me the fuel pressure regulator is the source of your problem. Are you sure you didn't cross the fuel lines? Thinking the fuel runs from the filter, through the injectors, to the FPR and then back to the tank.

So, I finally got around to doing a fuel pressure test, and this is definitely the issue: 66 psi!

 

So, I think I'm going to end up replacing all of my fuel lines (feed and return). Does anyone have any suggestion on what to use? Can I just use regular rubber fuel hose (MPI rated), or should I use SS braided hose, or something else? I'd prefer not to use hardlines, just because I don't like dealing with unions and bending that length of line.

 

I would not bother replacing fuel lines.

I would make sure the return line from the FPR to the tank is open however.

Maybe direct it into a gas can for testing purposes.

 

Give the FPR a few love taps.

pardon my ignorance but, what should the pressure be?

Thinking a little less than 40 psi. 66 pounds makes me wonder because I ran a little more than that when I had my 90 turbo wagon and never had a problem. OP may need new or cleaned injectors but I would still first suspect the FPR or he crossed the fuel lines when he reinstalled the engine.

I dont think it will even run if you swap the fuel lines (ask me how I know).

i doubt its a feul preshure problem the injectors control the flow not the preshure might make it a little ritch but not that mutch.

I thought I'd post my end results in case this helps anyone. I've finally got the car running reliably.

 

I did another fuel pressure test shortly after I did my initial fuel pressure test, but this time I did it on the return side instead of the feed. There was ~80psi on the return, which confirmed my suspicion that something was wrong with the fuel lines.

 

I made some SS PTFE feed and return lines, and replaced all of the lines from the tank to the engine. After driving the car for a few days now, the plug have cleaned themselves up (they aren't completely fuel fouled black anymore), and the car is running great, smooth as ever.

80+ on the return side?! Yeah that return line plugged up somehow. Kinda have to wonder where the obstruction came from though.

Glad you got it running.