My car was doing the following last fall when I parked:

- rough starting: easy cranking, but would take awhile to fire. Sometimes had to floor it to get it too start...then puffed blue-black smoke with gasey smell
- 'dieseling' on shut down
- badly fouled plugs: soft black 'soot', blackish wet 'stuff' on threads

 

Either a hole in the FPR or injector(s) leaking.

 

are all 8 plugs fouled?

 

Potentially a faultly check valve in the fuel pump. Install a fuel pressure gauge on the fuel rail test port to verify that the fuel pressure holds when the fuel pump cycles (not running).

 

All 8 plugs were fouled pretty much equally. I would assume that if an injector was leaking, the matching plug would show more fouling.
I have upgraded to larger 30lb SVO injectors (ECM not tuned yet) because I was thinking that an injector was leaking too.
I did put a fuel pressure gauge on the fuel line and it seemed to hold pressure for a few hours.
I do have AFPR but have not put it on...not sure if it's worth the money.

 

I think you answered your own question, you installed bigger injectors without reprogramming the computer

 

The problems were happening before I installed the larger injectors. I did this because I thought I might have a leaky injector and I wanted a little extra breathing room...injector duty cycle.

 

Larger injectors without reporgramming your computer will definitely cause you to run rich and foul your plugs. You may have another issue like your O2 sensors need replacing (will cause the car to run rich). I'd start with having the computer reprogrammed.