5.7 Gi stalling and surging after return to idle

[DB Cooper]

I have a 2004 Volvo 5.7 Gi-e that starts and idles fine until you rev it up and then return to idle, at that point it stalls. I let it sit for a few minutes and now it is surging when returning to idle. This is the first time I have started it for the season. I just changed the raw water pump, distributor cap, rotor, plugs and plug wires. It did not do this at the end of last season. The only thing that I did different is that I changed to a different plug, NGK BPR6FS instead of the AC Delco's the previous owner had in it. Can anyone help?

 

[DB Cooper]

Re: 5.7 Gi stalling and surging after return to idle

I just saw that I put a shorter plug in and it is a Vortec head which requires the longer one, could this be part of it? Regardless I am changing them.

 

[DB Cooper]

Re: 5.7 Gi stalling and surging after return to idle

Changed spark plugs, runs like a champ.