My son bought a 92 F150, 5.0 auto 4WD with dual flowmasters, shortbed. The 02 sensor is gone along with the cat. I replaced all vaccuum lines including the rusted out vesser canister. I cleaned the IAC and wiped down the throttle plates. We still have a fairly high idle, any suggestions. Also where is the TPS and could this be a problem and what does it do? Thanks for any help.

 

I think you're on the right track by first looking for a vacuum leak. Check your gaskets on the intake manifold and air intake plenum - I once found about an inch-long section of gasket missing between the plenum and manifold. There are several ways to check this - one is to take a spray bottle of water and conservatively spray along the gasket lines, looking for anyplace the water looks like it's being pulled in.

Suggest that you consider getting an oxygen sensor hooked back up - the computer will be running in its default configuration, meaning that the engine will probably run a little to the rich side. As for the cat, that's up to your conscience or passing any required vehicle inspections.

The TPS is located on the bottom of the air intake butterfly assembly. When mine failed, the engine would idle or hold any steady RPM fine, but throttle changes caused severe sputtering and bucking.

Hope this helps, and let us know how it turns out.