Hello,
I have a '94 940 wagon with, I believe, a 20 gallon tank. When I first start my car it has a very rough, surging idle, as if it is running on only 3 cylinders and there is virtually no power. The car will barely move. Then, after 30 seconds or so, the idle gets better, although not perfect, and the car has more-or-less normal power.
The fuel pump located directly next to the fuel filter has started making a whining noise.

I have two questions:
The most important is, what could the problem be? Does this pump need replaced?
Second, is, I am confused as to whether I have a pre-pump and then this main pump? I read in the FAQ that my year car should only have an in-tank pump.

This may be a red herring, but when I noticed it wasn't running well after a 30 minute drive, I popped the hood to find the air intake hose had come disconnected from the MAF sensor due to a loose pipe clamp. Could gunk have gotten some where causing fuel flow problems because the air filter was being bypassed?

Thanks again!