My truck recently began having some odd idling problems. Truck start up and warms up fine. However when driving, and depressing the clutch to change gears the engine revs up to what I would say at least 2000 rpm (no tach). And the length of time it revs high varies, sometimes only a few seconds, and sometimes it will stay there until I tap the throttle. Is my problem simply a bad TPS or something else? I checked/lubricated the throttle linkage and it all seems fine.

Also I just changed out my lifters on the weekend after a month of that annoying ticking. I though I would never hear that noise again, and I didn't for about a day, but now it is back, however not nearly as bad. Could there be something else wrong in my valvetrain? When I had everything taken appart I took a look at the pushrods/rockers and everything seemed fine. Just wondering if it could be something else.

Thanks in advance
1990 F-150 Reg Cab 302 5spd 4x4

 

The throttle / idle sticking is likely the throttle body & Idle speed control in need of cleaning . Is the valve train noise constant ?

 

I'll try to clean it out tomorrow. No the valve train noise isn't constant. Mainly when when I am gearing/idleing down.