I picked up a 1988 740 turbo 2 weeks ago. I had been sitting for a month before I purchased it. At first it would not idle at all, no power, and runs smoother at > 2000 RPM (with or without turbo boost). I've done the following with small increments of success.

1) checked/replaced vacuum hoses, oil separation box, intake manifold gasket.

When I put it back together it started and ran better. It now has a rough idle, but still no power up to 2000 RPM, runs smoother after 2000 RPM but lacking power.

2) Changed rotor/distributor.

The old one looked nasty, but not much of an effect on the rough idle or power.

3) Removed and cleaned the injectors.

The idle is better but still not good. No change in power.

When the engine is warm, I can shift into gear with out it stalling, but the idle drops so low the ABS gets confused and starts to pulse. Starting from a stop it takes 10 seconds to get to 30 MPH. MPG is very low; at idle the exhaust smells like a lawn mower (not an oil smell, perhaps unburned fuel).

Question: While the car is idling, I can remove either the spark plug wire or injector wire from the inner 2 cylinders with no effect. Is this normal?

What should I try next?