Tach jumping, engine hick-upping

[yellow81]

Hey guys, took the '81 out tonight, and noticed my tach bouncing at about 15-20 rpms. Only in between does it seem to do that which was approx. 35-40 mph I believe, a decent through town cruise speed. At the time it does that I can feel the engine "hick-upping also. Could it be my plug wires, they do need replaced, there is one that the coating is cracked, but it has been that way, and I'm just noticing this now. Also my computer is telling me that my oxygen and manifold temp sensors need checked/replaced.
My other problem/question is at idle, I'm at about 11 grand. Is that normal?
Thanks ahead of time,
Brian

 

[offshore]

yes your wire could be the cause (and you already know you have a bad one) dampness would make this even worse. my recomendation is full tune up. cap,rotor,plugs,wires(not one wire) & "ign.module" the reason I say module is the insulation on the wires gets burnt and they have a tendancy (my spelling sucks) to short.{ign module is cheep and while your in there you'd be nuts not to change it} Tune the car"check for vacum leaks at EVERY hose" (clear codes) Start the car warm up run the car with P/brake on @ 1800 rpm for 1 min. ( this will burn carbon off O/2 sen.) Take the car for a ride Both in town and h/way. recheck codes. (P.S. the last eng. I worked on that Idled at 11,000 rpm was a avco/lycoming agt.1500 wot. was 100,000 rpm I hope yours is 1100.) (little joke) Good luck and your prob. is most likley minor.