I got a SES light and checked the code and it was P0507 which is for high idle. For about a week I've noticed it has been harder to brake (higher idle RPM) and then just the other day I got the SES light. In park the RPMs are at 1400 and when I shift into neutral while on the highway or pulling up to a red light the tech revs and sits at 2000 RPM. I checked the vacuum hoses and they too like they are on fine. What else can I check before I go into the mechanic?

This is for a 4.8L Gen III

 

Pull the IAC valve and clean it. Use throttle bode cleaner...

 

Found the problem!!!! The second throttle cable was stuck and not allowing the throttle to go all the way back down.