Ok, I am back at it already. After driving my 1973 Volvo 164 with a Delphi fuel pump three pumps, I now have to switch out fuel pumps again. It has very poor acceleration and it always does "great" whenever I switch fuel pumps, but after a few short drives, the same sluggish behavior reappears. I know it is the fuel because when it gets sluggish, I have to throttle the gas to make it go better, and it usually results in backfire through the tailpipe. I now have a remanufactured Bosch fuel pump that is OEM. I will try to switch out pumps tomorrow. Can anyone offer any other ideas? Is anyone interested in a excellent condition white with original light blue interior Volvo? I think I am at my wits end on this.