Volvo Repair: rough idle/loss of performance 86 240, volvo 240 dl, fuel pressure regulator

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).

Your attention to this is GREATLY appreciated!

Answer
Kyle, first take that haynes manual and throw it away.  It gets people into trouble.  The true test of a faulty air mass meter is to run the car, unplug it and when the car starts to surge, plug it in.  If car stalls then the meter is bad.  What did the tech use for a regulator?  Anything other than a bosch regulator is nothing but garbage.  I have seen this first hand when Joe's garage put in a regulator from Pep boys.  Car ran horrible and had no power.  I put a spare bosch in and the problem went away.  How much were they wanting to charge you for the meter?  Roger