Alright, my dad (the 25 yr mechanic in the subject) and I cannot figure this out, so maybe someone on here has run into this problem.
My 318I have 249,9xx miles on it.
What is happening;
When the vehicle starts up, it runs perfect. When its cold it maxes out its RPMs at ~4200 (Just after 4, before the line for 4500).
As it warms up, it lowers until once at normal running temperature, it maxes out at ~2100 RPM (barely past 2).
My dad and I have checked everything we can except replacing the ECM.
Here's a list...
Air Mass Flow Sensor (replaced)
Crank Shaft Sensor
Cam Shaft Sensor
Took the Exhaust off just after the header to see if the cat was blocked, ran the same.
Replaced the ignition coil
Replaced spark plugs
Spark plug wires are 2 months old ~ runs to good at start to have one faulting + I know what this feels like and have fixed this recently.
Checked for vacuum leaks
No Engine Codes, well the one we get is unlisted in the Chiltons Manual,
Local Engine shops offered to diagnostic it for $90.00/Hr -- if I had this kind of money I'd go buy another e36 318i, since they refuse to give a time estimate.
Any help would be greatly appreciated. Note : My dad is a deisel mechanic and american cars are is area of study, so this is his first BMW too.