New to the SC need a little help please

BigSteve1967

Registered User
I recently got a 90 SC auto, 99000 miles and just had the Rad changed.
My question is once in a blue moon it will all of a sudden buck like a bull and when you pull over and put it in Park or Neutral the RPMs will rise real fast then drop then rise and drop? If you shut the car down sometimes it will be very hard to turn over but a minute or so later the car ran as good as new. I know its probably something real simple and I tried the SEARCH but couldnt find anything close to my situation. Any help would be appreciated.

Thank You Very Much

Steve
 
wow that could be a few things mostly bucking is a bad spark plug , but the hard cranking sounds more like the crank or cam sensor , it could be dirty injector i like stp gas treatment , i think mine idled stange like that when my connection on top of my gas tank was bad loosing power to the fuel pump. but if they had the battery unhooked putting in the radiator it may take a few days to relearn to idle mine took about 3 days and about 200 miles before it idled right again . onetime i had the throttle body off and it idled at 2000 for a week until i unhooked the battery for 10 min to reset the computer then it was fine ever since
 
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Assume lots of little problems.

I would start with checking and if you are unsure, replacing the plugs and wires.

Then check all connections for a vacuum leak. Make sure the SC tubes are seated tightly and that there are no air leaks.

Then see what problems remain.
 
check the cam sensor first it's about $32 and is cheaper than plugs and wires and easier (15-20 minutes). That was what was causing my car to buck. I would pull over turn it off and back on and it would run fine.
 
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