2002 Chevy s10

Possible plugged up catalytic converter.

There not one on there it got cut off and I'm getting bad gas mileage

It helps so much when people leave out pertinent information. The computer cannot run the engine properly without the information that the O2 sensors send it. Reinstall the cat and the O2 sensors.

Very likely a plugged catalytic converter since the engine starts getting hot. Take the exhaust loose at the exhaust manifolds or any where ahead of the catalytic converter and if it runs fine, it is the converter. Also, if you don't get much exhaust out of the tail pipe when someone steps down on the accelerator pedal before your take the exhaust loose, is a good sign the converter is plugged.