My 01 7.3 PSD does the same thing. Have had it do it off/on for the last 3 years. The Ford Stealership replaced the EBPV and it seemed to work OK, but I've have had it happen again at 40+* weather on down. Never two days straight, and always when you don't expect it to do it, Like pulling into traffic. Since I put on my Gauges, I noticed that there's no boost until it warms up and turns off what ever is causing this issue. It does'nt matter if your foot is partially depressing the Gas or all the way down to the floor.