I got 2001 Ford F-150 5.4 v8 when I crank it up in the mornings and drive it to work or wherever when I put in park it the rpms go up to a constant 4k rpms but now when I let it warm up in the mornings and drive it. An go put it in park its fine I have replace TPS 3 times and the idle sensor twice idk what to do at this point I even went replace my intake manifold it still does it can someone help me plz!!!!

 

Check the PCV system, from front to back.

 

Yup x2 of Jbew.

Either vac leak, IAC, TPS or Stuck throttle cable.

 

Make sure you have the Motorcraft PCV valve or it will contribute to the problem.

 

Why would that pcv be the problem

 

Let us know what you find.