GMC Repair: 1995 Park Ave, temp guage, engine coolant

Question
Hi I have a 1995 Park Avenue that is having a couple of problems. I bought this car in January and after about 2 weeks the engine light came on. I took it to a local Chevy dealer first time they had it they replaced the engine coolant sensor. I left the dealership and the light came on. Brought it back a week later they kept it for the whole day couldn't get the enging light to come on but on the way home, 2 miles away, the light came on. The engine light still comes on but not everytime the car is driven. For the last 2-3 weeks I have noticed the car seems like it is going to stall sitting at a traffic light just after startup when the engine is cold. When it seems like it wants to stall the little light next to the temp guage will  flicker on. This light will also flicker when I am driving down the road even after the car has warmed up but I don't feel the car trying to stall. I have not had the car tuned up since I bought it and was going to take it in to a local repair shop I have taken other cars to. I just wanted to know what you thought might be wrong with the car. Any help would be appreciated. Thanks Bob  

Answer
Usually when a coolant sensor fails it floods the engine with gasoline which gets into the engine oil and causes the OXYGEN SENSOR to illuminate the check engine light on occassion.

Change the engine oil, oil filter and the spark plugs and see if this fixes your problem.