Hello,

I currently have a 1990 Volvo 240 DL Manual 5 Speed. (Recently Bought)
About a month ago I was experiencing some hesitation (In all gears) and studdering/Idling problems. I took it to a mechanic and apparently the previous owner had wired in an 850 AMM into the car? The mechanic said he is unable to fix it or even correctly diagnose the issues until I have the correct AMM, and of course he will not be able to perform any "after market" such as replacing it.
I've decided to check local junk yards for a replacement and a wiring harness, as a new/refurbished AMM online seems to be pretty expensive.
Thankfully, I have a friend who will replace the 850 AMM with the new one.
I guess my question is do these/most of symptoms point towards the AMM issue?

Current Issues:
1. Hesitation in all gears and in Acceleration.
2. Idling almost always and sometimes very rough.
3. Will occasionally stall when I'm stopped unless I keep my foot on the gas.
4. Slight Rattling/Ringing noise?