while driving truck around town it drives great then i will come to a stop and it will idle high over 2000 rpm, will not shift gears, this only happens in the summer months, help please ps is a automatic with over 150.000 miles

 

You might get some help here but there is a specific thread regarding that generation of trucks and if someone else has a similar issue, they could be of more help.

Click on "models" - "f-150" - "1997-2003"

Good luck.

 

Moved to correct forum.

 

One thought is a vacuum leak (additional air getting in after the throttle body), but not sure why that would be only summer months.