light comes on at idle then shuts off going down the road. Rpms go up and down like it is shifting when keeping constant speed. Just replaced plugs and wires thinking that was it but it's doing same thing still. Check engine light codes were 21 and 41 but checked today and it was only throwing 41
JA: Does the light stay on, or does it blink?
Customer: It will stay on at idle like when I'm at a stop light and then shuts off when I get up to speed again
JA: What is the model/year of your Chevy?
Customer: 1985 chevy k10 5.7l carbureted
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: Yes. Well I have a mechanic that works on old trucks and he showed me how to read the codes. I've replaced spark plugs
and wires, cleaned air filter, and replaced ignition control module under distributor cap
JA: Anything else you want the mechanic to know before I connect you?
Customer: Yea also the reason why rpms are going up and down like it is shifting when keeping same speed level ground