rpms and a jumpy tach

probably unrelated but had my lower intake gasket replaced 2 weeks ago on my 01 monte (still saying low coolant btw) and since then, the car has no get up and go and seems bogged down. it has been "missing quite a bit and when its in cruise, the tach jumps around alot...mostly when on straight non hilly road. also does anyone know the typical rpm for 55 miles an hour? does 1200 sound about right...i never really paid attention to it until all of this started and it seems not right...but i know less than nothing about cars...

thanks in advance...

1st off, welcome to the Forums. These cars are notorious for injector problems. I'd also have teh car scanned to see if there are any codes stored. The low coolant sensor is probably mucked up with oil deposits and is malfunctioning due to the failed intake gasket. It is located in the passenger side radiator tank about 1/3 the way down.

thanks for your reply...had the car scanned again and they actually got codes this time. misfire in no. 4. so had plugs and wires changed. we'll see how it goes now. also changed fuel filter...boy was that thing nasty.
anyway...thanks for the input!

Erin