my 93 corsica jerks and shakes when i let off of the gas when im going anywhere from 45 mph and higher. does anybody have an idea of what the problem might be?

Sorry to say it could be a lot of things, but, sounds like an engine miss. I would check for trouble codes (has check engine light ever lit up?) and start from there. Could be a plug wire, coil pack, plug, EGR valve, the list is long. If it is a 4 cylinder, a weak cylinder will show up more than a 6 cylinder. You should be able to get a code reader pretty cheap for this car (around 25 bucks) at Advance Auto, or, perhaps they can even scan the computer for you. They can on newer models, but, since yours is OBDI they might not be able to. If you get no codes I would start with a complete tune up, plugs, wires, air filter, fuel filter, and clean the IAC valve and the area around it. Might want to pick up a Haynes manual at Advance also, (around 12-15 bucks) to guide you. Check you vacuum lines too, especially the one going to the MAP sensor (small square sensor) as the hoses will leak after several years. If there is no steady miss when idleing, these things should help your car run better. If you have a steady miss at idle, and these do not help, could be a failing coil pack or ignition module. These cars are generally not too hard to figure out, have had a 91 since new. Will go 200K miles if taken care of.

yeah the check engine light comes on but its usually if ive been driving for about 15 mins. its a 6 cylinder, if that makes it easier to figure out whats wrong. and thanks for the help.

Yes, that should get you pretty close. Be sure not to unhook the battery for any reason until you get the codes. Some items will fail and not set codes, but if you have them you will be able to start looking. You might be lucky and only have to replace a MAP sensor or Oxygen sensor.