Could a bad cat cause all the problems I have been having.
https://www.f150online.com/forums/sh...hreadid=122647

When I got to work today, I picked up a bag off the pass. floor and the floor was hot. Could the cat be on its way out, and that why I get the bad idle?

If its going I will pull it and put a pipe in place of it.

 

I thought we covered that, but maybe not. If your cat is becoming clogged, you will notice a drop off of power at higher rpms at first, eventually followed by a rough idle. The easiest way to test and see is with a vacuum gauge. After the engine is warmed up, connect the vacuum gauge to a manifold vacuum source, and start it up. Let it idle for a minute or so, just to make sure the gauge is steady. Observe the reading the gauge is at, and leave it alone for 10 minutes, while idling. That means don't touch anything. Even depressing the brake pedal, or the gas pedal, will effect this test, so when I say don't touch anything, I mean don't touch anything!

In fact, go make some coffee, or fix breakfast, or something that will occupy you for ten minutes. After that time, return to the truck, and observe what the vacuum gauge says. If the reading is lower than it was when you started the test, the exhaust is restricted. The more the reading has dropped, the worse the restriction. If it's 5% or more, you need to replace the restricted part, which is likely to be the cat.

Take care,
~Chris