engine reving, slowing down on 1995 Saturn SC1

I just replaced the entire cooling system and did a small tune up including, fuel filter, air filter, oil filter, and transmission filter. and replaced the sparkpulgs and wires. well now when im driving the engine will rev upto 3 and above and not switch gear, then sometimes i will have to completely stop to get it to switch other times, it will slow down and go no more than 20 mph and thats with the gas pedal floored, the transmission was replaced before it got it, and they said it only has a timing chain and no belt. keep in mind this doesnt happen everyday, its very random, and some days my car runs like butter, and i'm so scared its just gonna quit cause it seems too good. anyone have any insight into this problem I called midas but they want me to drop it off for a day so they can charge me an arm and a leg.

by in Hamersville, OH on September 15, 2009
3 answers 1 comment
ANSWER by on September 15, 2009
Diagnosing these type of intermittent problems is very difficult, and can be expensive due to the time and expertise needed to perform this type of job. I would consider a high quality independent or the dealership, and take a technician for a test drive to demonstrate the problem for them. Taking the car to a lesser qualified shop may end up costing more in the long run.
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COMMENT by on August 24, 2010
Try checking the cadillac converter. Had problem with the inside being loose. Fixed it and it ran like a top.
ANSWER by on September 03, 2010
you may want to try using propane or acetylene at a very low setting. Start your car and hold the torch (not lit) close to the intake manifold and see if it revs up. If it does you have a leaking manifold gasket.
ANSWER by on April 01, 2011
You said you changed transmission oil and filter. Had the same problem. The third gear valve was sticking. You should have a check enging light come on, though. If that is the problem, try a transission oil flush first. Might correct the problem.