Howdy and welcome to TRS.
There are many things that could cause your problems. I'm gonna assume fuel injected.
Tires too big for the gear ratio.
Bad sensor. (O2, MAP ...)
Bad state of tune-up. (Plugs, wires, distributor cap rotary button, clogged air filter ...)
Leaky fuel injector.
Stuck wide open EGR valve.
Timing is off.
Electrical or mechanical failure of some kind.
Those are just some of the possibilities that immediately come to mind.
We can narrow it down but it means checking many things.
First off: Do you have any check engine codes?
How To Read the Codes
Code Definitions