I have an 86 240 wagon with 175,000 miles (estimated). For the past few months the car has been hard to start taking several 15 second cranks to start up. After the hard to start, it ran fairly fine, though sometimes the idle was a little rough.

Tonight it finally acted up enough that I cannot drive it. The car will barely start and the engine makes a popping sound, like pop pop pop, as if it can barely sustain its combustion. The sound is low and and the car shakes while its running. Its not a backfire, and It lasts for about 5-10 seconds, and with increased gas pedal, just speeds up a little before dying, still making the lugging like noise.

And heres the kicker. I started it up about 45 minutes before it started doing this. And it had cranked right up. I let it idle for about 10 minutes, then cut it off.

On edit: its more like a cough than a pop.

New fuel filter a few months ago (after the problems started)
Plugs look good.
New coil
Cap/rotor good
Couldn't find any vaccuum leaks.
Mass air meter unplugged resulted in same sound, but ran 1-2 seconds only.
New 25 amp blade fuse and holder.
Fuses Clean and new
Cleaned the throttlebody a while back.

My thought is low fuel pressure, and possibly a new fuel pump or relay.

And where is the fuel pump relay? I looked under the glove box but didn't see it.

What do you guys think?