my truck has been doing this for a while. first off its a 1990 f150 4.9l with a 5spd manual 4x4. my problem is that when i am driving, doesnt matter whether its cold or warm, when i push in the clutch sometimes to shift it wants to rev up around 3500 rpm. sometimes it will come back down to normal rpms, but sometimes it just stays right around 3500- 4000 rpm range. what could be causing this?

 

This happened to me once. Look where the throttle cable connects to the gas pedal and see if the cable is starting to fray where it passes through the firewall.

 

will do. did you have to replace the cable, if so how much was it?

 

Less than $10 from a pick n pull yard. Mine was hanging on by about three threads.

 

i didnt see where it looked like anything was fraying. there are 2 cables coming off my tb one goes into the firewall the other goes into a big cannister looking thing, what is this cable for? they both hook to the same linkage.

 

That's the cruise control.

Since you're talking about the throttle cables under the hood, I'm just making sure you didn't misunderstand me - I was talking about where the cable goes into the guide behind the pedal.

 

yeah thats where i looked first, but didnt see anything so i looked under the hood. could this be a tps problem? i know i dont want to try and fix it by just buying a bunch of new parts, i tried that already on my intermittent wipers and it cost to much money to do that.

 

In order to rev that high it needs air and fuel. It's got to be throttle or linkage related. If the cable is working OK, do the throttle plates move freely? Any chance you can take the throttle body off and clean it out real good?

 

they move freely, when it first started this i took off the throttle body and cleaned it really well with carb cleaner, but that didnt seem to help

 

it doesnt always race up some times it will do it gradually some times it will stay put then drop, and some times it will race up stay or go back down. really confusing

 

Replace the tps. this happened to me as well on my 88' and that was the fix.

 

alright i will thry that i suppose

 

i also forgot to mention that the 88' was reving up to 6grand and hittin the rev limiter, so i think that help ya'

 

the most mine has revved up to is about 38-4000 rpm