1988 chevy cavalier rs idleing and driving issues

k so I recently bought this cavalier about a week ago its and 88 automatic trans with 1.8 4 cylinder I thing not that it matters much. I noticed the exhaust had a smaller pipe from the manifold and the rest was strung with a bit bigger pipe and was attempted to crimp the pipes togather it was loud so I crimped thhe pipes better and used exhaust glue to patch the holes it runs better now to a point. but when I start the car it revs up a fair im guessing 3 grand since I have no rpm gauge but then it dies down to a low idle to the point were the car shakes a little bit. with the exhaust fixed I can get it up to 20 kilometres an hour with my foot off the gas when I turn fully it wants to lurch ahead/backwards. when I took it out for a highway drive today I came to a stop sign so I slowed and stoped and the car stalled out. started no problem. but I also tried later putting it in neutral and it doesn’t stall as I role to a stop it doesn’t shake in neutral. I would like to have this fixed but I need some pointers as of were to look. im not sure if this means anything but when I got the car it had a bad enough radiator fluid leak at the hose meeting the heating car on the engine side of the fire wall I repaired that and no longer leaks. any sugestions on what I could do do fix the lurching and staling.


Clean the throttle body first

If that doesn’t help, the idle air control valve is probably defective

Make sure you don’t have any obvious vacuum leaks