86 740 Turbo wagon. 161111 miles. Rebuilt turbo, new catalytic converter. New fuel pressure regulator in the last 2 months. Wrote here a few days ago about my catalytic converter becoming restricted. Ordered a OEM cat and had it replaced yesterday. Since it was a direct fit, I didn't think I needed to go to the dealer for the replacement. The service station mechanic says he test drove the vehicle, driving it about 10 miles after the replacement at 65-70mph and said it ran fine. Yesterday evening when I came to pick up my car, when I first cranked it as I was about to leave the service station, it seemed to have almost no compression but it cranked quickly as expected. Mechanic then sat in the seat and cranked it, and it seemed to be fine. So I drove it home (about 15 miles) and during the last mile or so it seemed to feel almost restricted again, but not nearly as bad as it was with the old catalytic converter in it. Previously when I would disable overdrive there would be an immediate boost, yesterday there was none of the familiar torque "build up". So I called the mechanic when I got home, and he suggested that we check the plugs which may have become fouled from blow-back when the converter blocked up. This is a new mechanic for me, and I don't have a lot of experience with these matters. Does the plug fouling seem a reasonable explanation for the loss of power? To make matters worse, went out to start it this morning to take it back to him, and it wouldn't even crank until I hold the accelerator half-way to the floor and hold it there, and then it runs like it's being starved for air. As soon as I take my foot off of the accelerator, engine cuts off. I looked to see if possibly a vacuum line was off and didn't see any that were not connected. Any ideas on this? Is it reasonable that the plug foul might cause loss of power? Any thing that should have also been cleaned/checked with the swap of the converter? Help. I miss my car already.