Engine Performance problem
1991 Cadillac Brougham V8 Two Wheel Drive Automatic 192000 miles
My car idles rough anytime I drive my car over 55 and then I come to a stop it will idle rough. To fix this problem, I floor it between 40 and 55 and it fixes the problem. I think there is leftover gas in the cylinder and not all is burned off and leading to power leftover in a cylinde ror two. I changed the spark plugs and wires and that handled the idle better. I have been told on eof the cylinders may be failing and my car does burn oil at its mileage. I am wondering if my valve seals are abd or if my cylinders are losing compression. Please Help.
I have replaced the following
All Vacuum Lines
Speed Sensor at transmission and drive shaft
Fuel Pump and Filter