I have a 1986 740 turbo with 218k on the odometer. In the past month it has developed an irregular/frequent miss at idle. The miss is present when the engine is first started and when it warms up. Upon acceleration, the problem clears up and there is plenty of power. The problem seems less prominant if I have the air conditioner running. In the past few weeks, I have checked/replaced the following:

Replaced: Plugs/wires/cap/rotor/Hall effect sensor
Checked throttle body (clean and shines like a new one)
Ground points in engine compartment (I do have an updated wire harness)
Checked ignition timing

Can anyone point me in the direction of other possible causes? I considered checking the ballast resistors, but I can not find any specs as to how much resistance they should read. I read that cruddy injectors produce similar symptoms. Anyone have any greentops in good condition they want to sell? No one services injectors in my area.