I have a 95 D90 SW with 110k that is surging (for lack of better description) between 1500 and 3000 rpms.
It does not do it when idling or under full throttle. When sitting still you can rev the engine and the issue is present.
The check engine light is not on and there are no codes.
It does not seem to be spark or ignition related more like fuel metering.
A strong electrical load on the system, such as turning the ac on or turning the fog lamps and head lamps on at the same time, seems make the problem worse.
What I've done so far:
Cleaned the Mass Air Flow Sensor
Cleaned the IAC Valve
Checked the engine wiring harness for loose connections / damage.
Wires Cap and Rotor look good.
Any helpful input would be greatly appreciated!