i biought the truck used with 112,000 miles and it seems like it idles a lot lower then my old 2001, could it be bc its a 5 spd and not an auto? either that or i thought it coukld be a vacuum leak.

any advice is appreciated, thanks.

 

The cause could be from several sources but I would start with the PCV tube that connects on the passenger side of the throttle body. It is right under the top radiator hose. Look for a rubber elbow that connects to the throttle near the front. This elbow tends to deteriorate resulting in a vacuum leak or it can partially collapse.

I had a tough time finding my rough idle problem and finally lightly sprayed starter fluid around the throttle body until the engine surged. Upon inspection of the elbow I found it to be in bad shape and was cracked. I replaced it with a silicone elbow and the problem was solved.

 

is there an aluminum throttle bosy and upper intake for the 4.0 sohc?