I just bought a 2006 Pacifica in March. Same problems, fuel tank goes from half empty to empty. I noticed 3 days after we bought it so luckily the dealer said they would fix it. I just got the car back after about 2 MONTHS! and 4 times of trying to fix it later its FIXED. They started out by replacing the tank, then the canister, then the instrument cluster, and somthing else I dont remember. The thing that finally fixed my car was they replaced BOTH fuel pump moduals and BOTH sending units. If my dealer wasnt fitting the bill for me it would have been thousands. It took THREE different dealerships to fix it. Two were Chrysler dealers. The tank and canister alone was $1200. The bill to the dealer for just the pumps and sending units was $800. But like I said, now its fixed. YEA!!!!!