today while driving my truck started to idle wierd. the rpm would go up to about 1800 then down to 900, runs fine while driving. i have replaced the pcv valve the grommet was destroyed, didnt do anything. also while i was driving i left it in second no gas and the truck kept going kinda of like how and automatic does when you let off the brake. i am lost i read it might be the mass air sensor? please help this is my daily driver.
well i fixed it there was a loose screw on the throttle body this guy was causing me all that trouble

Thats a good start with the MAS,look at the EGR too