I am suspecting that my 94 f-150 may have a plugged catalytic converter. My mileage and power are suffering even after a complete tuneup (new plugs,wires, cap, rotor, and filter). I have a laser temp gun and measured the temperature on the inlet and outlet of both cats. They both had about a 40 degree difference, with the hot end on the inlet. Does this sound like a plugged cat to you guys??

 

If the cat has never been touched there is a good chance its clogged. A pipe or broom handle will unclog it.

 

A plugged cat will cause overheating, backfireing, if you have a stainless exhaust tip, they can turn gold due to the excess heat, you can also wind up with a fire in the carpet from that. The big thing... After a drive on the highway, they will glow red.

 

A Carsound's high flow cats will improve your flow.
Drill a hole upstream of the cat, throttle it hard in neutral,
if it's plugged you'll feel the exhaust back pressure.
Worse would be to Mig the hole shut or replace the cat.
The high flow cat flows just detectable vs an empty cat but legal,
passes smog tests with ease provided everything else
is in proper tune.