Hi, its a 1995 2-door 4.3L Vortec V6 chevy blazer w/ 150,000mi. When I start the truck, it was alright for about 5 seconds (this morning) and then I can hear clicking about every 3.5 seconds. On the 1st click, the engine throttles down from 700rpm to about 500, and about a half second to a second, (varies slightly) a second click occurs, and it throttles back up to 700rpm (< i> all in idle state< /i> ) When I am driving, it continues, and you can really feel it. I fairly certain it happens more often when you are rolling, but I haven't timed it.
I do generally have to tap the gas to get the truck to start, and wasn't sure if this would be related or not.
I've had this happen once before. It went away after a day or so, so I wasn't able to trouble shoot much. The last time this happened, and this time, the drivers window will raise, but not lower. When you try to lower it, the E-Brake light kicks on in the dash, and the rest of the internal lights dim (have not checked headlights).
Makes me wonder if the window motor is shorted and you are hearing the breaker kicking and feeling the alt load down the engine in response to the voltage draw. Try removing the silver circuit breaker in the fuse panel and see if it still does it. PM me back