I happily own a 1986 volvo 240 dl wagon with 215k miles. The vehicle recently was repaired for a faulty fuel pressure regulator (symptom: start, immediate stall); the vehicle now starts and runs. After installing the new regulator, the mechanic noticed a rough idle, and diagnosed a poor/faulty air mass meter and fouled plugs. I declined replacement of the AMM, due to it's high cost, but had new plugs installed. I've driven the vehicle approximately 200 miles since this most recent repair; the vehicle is, in fact, idling roughly and getting poorer (than normal) fuel mileage. I'm relatively savvy with this vehicle; I checked the air mass meter according to the Haynes repair manual, to confirm the mechanic's recommendation. The resistance accross the specified contacts is supposed to read 3.5-4.0 ohms; mine reads 3.0. Does this deviance from the acceptable range warrant a replacement part? The air mass meter in this vehicle is the original part. I've checked the air intake hoses for leaking/cracking, too, and can't find a vacuum leak.

Additionally, is it possibile that the problem with the fuel pressure regulator could have been caused (in some way) by a poorly functioning air mass meter? (this was the second regulator installed in 15 months/20k miles).

I have relatively good mechanics skills, and I'm willing to attempt any investigation you recommend.

Your attention to this is GREATLY appreciated!