1994 F-150.

Upon shifting at 2000 or so rpm, when the clutch is depressed, the engine revs up 400 rpm or so (for the last week).

If 20 secs or so passes, the rpm will begin to fall.

Also should be noted the engine is idling at about 1100 rpm for the last week.

used to idle around 800 rpm.

I am in PA and the Temperature is cold, but this problem did not occur last year.

thanks for you help!!