If your O2 sensor is out, the check engine light would be on. Why would you take it to a place with a bad reputation for over charging? Yes an o2 sensor can cause High idle. You need a code reader to find which one is bad, will display a code. Unless your check engine light bulb is burnt out any bad sensors It would be on The 97 Bonneville is well known to have all kinds of electrical problems too I owned one it was a POS I'll never buy another one again Its not a cylinder The bad reputation shop told you that to charge more money for an engine rebuild Take it to an actual mechanic

Hope it helps

Lr

Why would you take it to a shop with a bad rep? It isn't a cylinder. Could be your transmission isn't shifting when it should. Heck, who knows? Find a reputable shop..or you could change the 02 sensor...but, I have my doubts about that affecting rpm's. Do the rpm's drop after a bit when you start it or do they stay at 1000?

high rpm at 35 isnt a 02 sensor more likely a transmission problem

It sounds like the problem is you parted with your money before taking a test drive. Try a different repair shop.

it could be the idle air control sensor sticking ! get some carburetor cleaner, unhook the battery, take the sensor off and spray the tip on the sensor !

Not really, I bought the vehicle for $650 knowing the problem. Nothing else is wrong with it other than that.

I just recently bought a 97 Pontiac Bonneville with 160,000 miles. When I start it, the RPM goes up to 1. When I drive, only going at 30 mph, it will go up to 4 rpm, then drop down to normal once I get over 35 miles per hour. Auto Zone said it was just as simple as a o2 sensor. But I took it to a repair shop, (mind you this repair shop has a bad reputation for overcharging) they said it could be a cylinder. but they wouldnt know without running tests, and just checking it over is 75$ a hour. What does it sound like the problem is?