Volvo Repair: rough idle 86 volvo 240, volvo 240 dl, mass air flow sensor

Question
Dear Sir,

I happily own a 1986 volvo 240 dl wagon with 215k miles. The vehicle recently was repaired for a faulty fuel pressure regulator; 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. I declined replacement of this part, due to it's high cost. 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!

Answer
i dont thing fuel pressure reguletor go bad so fast but again what part did he  use aftermarket than is posible i know  volvo fuel pressure reguletor after you replace them one time it stays good for long time .but again  it sounds the problem  you have with mass air flow  resistance is good  but the readings from mass air flow to the copmuter are wrong and mass air flow sends those  wrong info .you can do your self the mass air flow  sensor  just buy  one i can help you if you close to chicago i know many place were the sale them cheap  best way to know for sure is take it volvo delaer pay $100 diagnosis and you will know for sure  most the time we just plug the new one in if is better than that is you problem and the will check you wiring  also  but any way good luck .