Volvo Repair: rough idle 86 volvo 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).

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

Your attention to this is GREATLY appreciated!

Answer
Greetings,
         Another way to check the operation of the AMM is to disconnet the wiring to it...see if it runs better..disconnected..if you decide it is a failed part...go to internet and seek out AMM rebuilders...the prices are considerable less cost...some AMM's can cost over $600...I have found prices to be less than $200...or...go to your friendly auto recuycler.. they may have a good one for $50.only use same number AMM
         2 fuel pressure regs in 2 years is excessive and probably a guess.
         There are a few other considerations...fuel supply.. ignition wiring and related parts ..check out dist.cap...look at spark plugs...what do they tell you?...failed electrical contacts can be a problem...make sure that your fusebox IS SUPER CLEAN W/O ALUMINUM FUSES...clean the contacts WELL!..add quality copper fuses
     Another consideration...in the gas tank there is a rubber hose that connects the intank fuel pump to it's output pipe...this rubber hose deteriates and can be a major problem because of poor fuel delivery...this is a complex job including the removal of sending unit and misc. fuel lines...if you plan on keeping this car...you might consider looking into the tank....these rubber connectors fail often.
               Good luck,
                        Bilbo