Ford ranger 2003 4.0

Idles fine in park and nuetral, But when in reverse or drive with with foot on brake at a stop the truck will idle high. once i step back on the gas and proceed it smooths back out and there isnt any issues. but it is annoyying coming to a stoplight and it starts rumbling pretty load.

any ideas?

 

Brake booster is gone. Is there white smoke coming from tailpipe when you brake? Whats basically happeneing is your getting a vacuum leak.

 

what would be the fix for this?

 

You would have to get it replaced and make sure the master cylinder isnt leaking brake fluid into it too. Iv never replaced one myself so i cant rlly tell u how hard it is. But im sure u can ind how tos online. Im sure its something anyone that owns wrenches can do at home

 

This happens also when my foot in not on the brake when i am coasting to a stop and in gear - this is an auto trans.. So could it be somthing other than the brake booster? I have changed the idle air control valve and pvc valve with no change. I am thinking maybe it is the MAF, i did once accidently clean the MAF with brake parts cleaner instead of MAF cleaner. Any thoughts?