Ok, I am leaning towards a bad ficm but I'm hoping for some feed back. Before I took the truck apart to put the single on it it had this issue as well. James told me that it would do that with a 1/4 tank because of the way he drilled the basket in the tank.. He lied, its full. I thought maybe it had something to do with the way he had the lift pump setup to feed more fuel when it senced boost, so I took that off and turned up the pump, for the last day before we tore it down it seemed to be working good lots of passes up and down the road no issues. This morning we took the truck for the first road test since the switch and it worked great, turned on hard, parked the truck messed with the TDV and went back out and sure enough the problem was back. When the boost starts to come on and it demands more fuel it will surge and miss at about 21-2500 rpm, I find it very strange that it would work fine this am and now its acting up, seems like it doesn't like it when its warm, and in my reading it seems kind of like a bad ficm but of coarse nobody seems to follow up on the old posts as to wheather or not they have solved the issue. I also had the fuel gauge drop off to 0 and then back to normal while driving, I read someone else with same issue and they replaced the ficm and it fixed it but still confused as to why it would be related. Truck has 80 overs, duel fuelers and the lift pump is a holly black, rated for 140gph at about 14 psi. I know its not a good pump either, we are just trying to work with the mess I bought, nice truck but my god its been a night mare. its an 02 lb7 motor in an 04 lb7 truck