I have a 1987 325i convertible (build date May 21, 1987). I just had a new timing belt installed. On the drive home up a local hill, I had the occasional stumble immediately followed by a strong surge. Just watching the gauges with the car running in neutral, the fuel economy gauge suddenly drops to zero, the revs drop and then surge before settling at about 800 RPM again. I've cleaned the ICV and checked the resistance - it's within specs. I've checked the resistance of the blue temperature sensor - it's within specs at all temperatures. I have a Miller MAF replacing the AFM so that shouldn't be an issue. Any ideas on what could be causing this? More particularly, is there anything that the shop would have disconnected or moved when replacing the timing belt that could result in this behaviour as the car ran perfectly up until the belt change?
Thanks!
Thanks!