My 94 e320 has idle issues. When it is first started in the morning car runs fine but when it warms up the idle flunctuates from 500-900rpm. When the check engine light came on I had the code checked and it was o2 sensor. Replaced it no check engine light but car still idles like crap any help is greatly apriciated my felow mg owners.

 

Have you had the engine wiring harness replaced. And has the throttle actuator been changed out. If not, those may be causing the problem, and will need to be replaced sooner or later because of the faulty wire insulation they used back then. It may start throwing random codes or going into limp home mode. I changed out both of those by myself in my 1994 E320 for about 1100 dollars. Got to search around for the best price, they vary a lot.

 

Sounds like a bad mass-air-flow sensor. It probably has been given warnings every now-and-then like the idle temporarily dropping below normal before adjusting itself or engine dropping rpm inbetween gears when the transmission upshifts. If it's the MAF, it's a simple fix. One way to test this is to disconnect the sensor and see if it works without the fluctuation. If it's the culprit (of which I am sure, do yourself the favour and purchase a new one). If you decide to clean it, it should for the interim as you prepare for a new one.