I have a `95 volvo 850 GLT automatic wagon which I bought about two months ago with 86,000 miles on it. When I got the car, it needed a mass air flow sensor. I replaced the sensor and the car ran fine. About a week ago the car started having problems during acceleration.
The car starts fine and then when you try to press the accelerator the car doesn't increase in RPM's or do anything except coast forward a little bit like it should do when in Drive and you don't have a foot on the brake. After about 3-10 seconds the car will drive just fine and accelerate normally. It does this every time I slow way down or stop at a light/stop sign. The problem wasn't very bad at first. It started by just happening once for a few seconds at one stop sign in the morning; but, It has gotten consistently worse. I can't even pull out onto a street anymore because I have no acceleration for so long. Though after awhile the car does accelerate fine...until the next stop sign then it happens all over again.
Like I said I replaced the MAF sensor. I also replaced the throttle position sensor. I also checked the fuel pressure and it was 35psi which I heard was normal. I've been searching for what this problem is and it seems like it has to be a control problem because the car runs fine on the highway(if I ever get there).
I would really appreciate any help or ideas.
---Matt

 

static pressure should be 43.5 psi roughly, If pressure is too low, pinch return hose by hand and check whether pressure rises.
If pressure rises rapidly, pump and lines are okay. Replace pressure regulator and recheck line pressure. If pressure rises slowly, fuel filter, fuel pump strainer or fuel lines are blocked. If pressure does not rise, good chance the fuel pump is faulty.

 

I checked the pressure with a tire gauge (I don't have a real fuel pressure gauge and didn't want to wast the money on one yet) and It was approximately 30-35psi and when I pinched the return hose rather tightly it jumped to about 50psi almost instantly.
I'm going to try to borrow a real gauge and check with it before I buy anything.
Is the pressure regulator something I can fix? Or is there a way I could get one really cheap?

 

the regulator is easy to replace it is towards the passenger side on the underside of the fuel rail. I would try to find on in a local junkyard, as they are 130$ even from FCP

 

I rechecked the pressure it was a little over 42psi. So that's not the problem.
My mass airflow sensor is only about a month old. The one on the car when I got it was bad and I bought a new one and replaced it. Today I unpluged the new MAF sensor (the advice of a friend) and the car accelerated fine. It idled terribly but that's normal with out the sensor.
Is my new MAF senor bad or the wrong one for my particular car or what?