[4dmac]

My 1986 SS stock 305 has a surging problem after you have driven for about an hour. I live in Phoenix where it is hot most of the time. When I am driving a constant speed it starts to pulsate, up-down, up-down a few rpms over and over. If you speed up not present, if you slow down, not present, at an idle not present, only when driven at a constant speed. Any help would be greatly appreciated.

 

[464elky]

check the TPS. They do not set codes unless full open or short. The windings get worn into just off idle after years of use. Lots of info here and on the web as to how to check it. When you get the meter connected move the throttle very slowly and watch for any voltage jumps or drops instead of a nice steady increase.