81 928 , 5 speed. Starts great , idles fairly steady. Take off and drive at steady speed/RPM and it seems to surge. It seems steady at higher RPM on hiways . Mostly early in drive cycle and at 35-40 mph. If I give it the gas it goes fine. I would guess could be : fuel filter, temp sensor, wires ? anyone have similar ?

 

Sounds similar to my '81. What I had was at times everything seemed perfect, then on some startups a almost imperceptible stumble and surging while driving. Problem turned out to be bad plug wire causing intermittent miss. (until wire fell out of plug, then it was constant miss) These were new wires so I never suspected looking there in my searching. Upon inspection the crimp was bad and did not hold properly. Used same length wire from old set and it has run perfectly since. Hope this helps.

 

I have this same exact problem on my 82 Auto, but it is all the time. A rythmic surge. I have not had a chance to look into it very deeply yet.

 

L Jet right? Coolant tempsensor and/or vaccum leak. I had both issues.........

 

I'm working with a similar issue... i feel it stumble a bit on idle, so possibly a bad plug socket and/or wire. [just changed the plugs, so I should probably go back and make sure they're all seated].