[djs]

I, too, had the mysterious bucking only at part throttle in my '75 2.0 for the longest time. It was more of a nuisance thing, as othewise the car ran fine. To address the problem, I replaced the TPS and adjusted it per spec first. This did not help.

Then, I attempted to "clean" the trigger points, if such a thing is possible, also to no avail. Finally, I replaced them (they had over 100K miles on them). At the same time, I installed new spark plugs, gapped to spec. The bucking has totally disappeared, but I'm not sure whether the trigger points or plugs get the credit. I get smooth application of power from idle all the way up, and I've been driving it for over a year with no further problem.

I suspect the trigger points, only because a new TPS did NOT seem to fix the problem. New trigger points are around $80, but on a car with over 100K, you could justify it as preventative maintenance even if it doesn't cure the bucking.

I still feel a noticeable transition when lifting OFF of the throttle at low rpms and speed, but this is only on deceleration and close to idle. On acceleration, there is no such lag. I think this comes from my '75's EFI being programmed to cut off the fuel when the throttle closes on deceleration, an emmission-related step. It causes no problems, but is definitely noticeable when the car is slowing down to near stop. Your '74 doesn't have this feature, I think.

So, to sum up, if you can rule out some obvious causes like a loose connection or ignition related problem, I'd replace the TPS AND trigger points if they are the originals.