I have a 99 Grand Prix 3.8 2 door, been in the family since 2001. Back when the 3rd recall on these came out for the oil leak and fire the car was parked for a couple years. This spring I got it out and have been driving it since with a few minor bugs here and there but nothing I haven't figured out. About a month of being back on the road, the fuel gauge would randomly drop to E then up to full then read accurately. This went on for several weeks with no rhyme or reason as to why it would stop and start reading correctly. Then it finally stopped altogether. Every time I start the car the needle is at full and slowly drops to E unless I'm in P or N, then for whatever reason it's a pretty quick drop. Sending unit and pump were replaced right before the car was parked and all tested fine last week when I was having wiring issues at the plug on top of the pump. Now there is a resistance going through the plug that changes as the float goes up and down like it should. What is the next step to diagnose this? I've heard speculation from others as to the cluster and various things but I hate wasting time and money throwing parts at something. Any help would be greatly appreciated.
