m50 idle surge problems

[davidflrs]

My 92 525i manual is experiencing an idle surge problem after warming up.
I get a transmission program error with an engine code of 1216 for the throttle potentiometer.

When the engine is cold, the idle is at about 1000 rpm. Once the temperature gauge needle is beyond the blue marker, the engine would surge between 1400 and 1900rpm. After seconds, the idle would jump up to 3000rpm. I dont know if the MAF is also a cause for my problems. Does anyone know of a site where I can functioning MAF or Throttle Body?

I couldn't find any related information in my Bently service manual so any thoughts will be greated appreciated. Thanks in advance

[BillionPa]

try the crank position sensor first.

[BillionPa]

the fact that it happens at a specific temp (after the ECU warmup cycle has ended) leads me to believe the ECU itself could be to blame, perhaps bad capacitors.

[BillionPa]

OR... the O2 sensor, since that only activates when the engine hits operating temp.