I have an 06 chevy colorado 4 cyl. auto. When I apply the brake and slow almost to a stop, the engine starts loping from 800 down to 300 rpms and then dies. I can re-start it and it will idle fine. There is no service engine light on. Anyone had tis trouble?
Sit at idle and just stomp the brake - does the idle lope and seem like it might head to stall? If so, you may have a leak in your brake booster or check valve.
If not, then I’d pull the idle air control (IAC) valve and clean it.
But I’d also make sure that all basic “tune up” items are up to date - plugs, wires, filters…
Thanks for the advice. I tried new plugs, but there aren’t any wires, boots go from coil to plug. Neat huh! The brake booster does’nt make any noise and seems to work OK. I will try the IAC valve, as soon as i figure out where it is. Thanks again.
The IAC normally sits right on top of the throttle body - right over top of where the throttle plate is since its job is to get air around the throttle plate. Just follow your rubber intake tube away from the air filter.
If the idle problem always (or, often) happens, as the vehicle slows to a stop, try this to determine if it’s caused by the idle air control valve(iacv): Disconnect the electrical connector to the iacv, start and drive the vehicle; stop a few times. How did the idle behave? If better, you STILL should clean the iacv and air passages with Throttle Body Cleaner.