Intermittent split second fuel cutoff after replacing timing belt.

[Ian 87 325ic]

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!

[MrBurgundy]

Check your CPS

pretty common for a diyer to not clip in the section of wire to the timing cover and the fan or WP pulley will snag it and damage the wiring.

[82eye]

I have a Miller MAF replacing the AFM so that shouldn't be an issue

with age they are now failing. if you do a search you'll find hundreds of posts with no fix. hopefully it is not the issue here.

[e30m3s54turbo]

On one of my e30 I have Split Second and a mass air from a Ford vehicle. I had problem with it a couple years ago. I contacted Split Second to ask what mass-air was in the kit. He gave me the information. I also did asked to he could send me detections how wire it up. I was able to check my wiring was connected correctly.
My was the mass air went bad.