I need some help. First time on here, but I have looked at other posts and did not find simular problems. I have a '98 Park Ave Ultra, and the SES light is on. Upon taking it to AutoZone they said it was a Speed Sensor, I believe codes PO503 and PO502. I put a new Speed Sensor in and still no improvement. Is there more then one Speed Sensor? These are my problems: #1 - When the car is in park, I rev the RPM's up and at 4,000 they stop increasing and get real choppie. #2 - While driving down the road the transmission seems like it is dropping into 2nd and 3rd gears, including every once in a while it will just stall with no engine lights or anything. #3 - The RPM's do not jump around but the speedometer doesconstantly while driving. Of course the RPM's do drop when the tran. drops into gear.


I do appreciate what help I can get. Trying to save the labor costs. Thank You.