Volvo: 1973 144 losing power in 4th, 4 cylinder cars, older cars

Question
Hi Ray,

On the highway my 144 loses power in top gear. It's a faltering kind of feeling, almost like a plug or a lead that has died. The power only resumes when I back off the throttle. The power loss is only in 4th gear, and the problem can be intermittent as the Volvo often pulls along well still. Also do you know of any decent parts sites relevant to my model apart from ipd.com?

Much appreciated,

Ben

Answer
Ben,
The parts for those older cars is getting real hard to find. The call for the older parts has fallen off so much that no that I deal with carries them any longer.
The intake manifold pressure sensor could be causing the loss of power and also the cams in the older 4 cylinder cars go bad. Fuel pressure could be weak or even a clogged fuel filter.