When I changed my battery out for being a bad battery thats when I noticed that when I was slowing down at a stop light or stop sign, when the motor is lowering the rpm's it would keep lowering even when I was stopped(below 550rpm). It would lower the Rpm's almost where the truck would die and of course this would lower the brightness on all my lights which makes driving at night a pain. I tried a new alternator that didn't make it stop so I tried cleaning the throttle body next maybe thinking it had built up and is creating a idle problem but no luck. Local mechanics can't figure it out and I have been putting up with this for 6 years! I thought about getting a programmer to adjust my rpm's higher which I think 500 to 550 is to low but thats factory. The programmer would it be putting a bandaid on the problem?