Cadillac Repair: 1989 Cadillac Fleetwood FWD rough at low speeds, 1989 cadillac fleetwood, r 134 freon

Question
Hi I have a 89 Fleetwood FWD 4.5L V8. After a few minutes of driving the car starts to bog down, becomes sluggish at take off and tends to buck especially when traveling at a constant 35 mph. If I take the car up to highway speed it runs smooth and constant but starts acting erratic again once I drop the speed back to city speeds. I attempted to replace the spark plugs but was unable to find a way to access the rear 4 plugs. I did the self diagnostic using the heat/ac panel and this is what I got 8.8.8, ..E, E13, ..f, F47, F.F., F47, .7.0 any help you can provide will be much appreciated.

Thanks, Tom

Answer
Replace the oxygen sensor and you have a problem with the freon pressure in the AC system.

If you changed the R-12 freon to the newer R-134 freon you will always have the F47 code due to the low pressure sensor is not factory calibrated for the R-134 freon and to date there is no fix that I know of except to go back to the R-12.

Once this is done CLEAR the codes from the computer.