I have 74' chevy truck with a moderatly built 350. around 420hp with 11.5:1 compression. OK my problem is. When I first start my truck it idles great,revs great. I put it in drive and take off, after the first 1/2 mile or so its start surging like its not getting fuel. Some occasions it actually dies. I role to the side of the road and start it. Its will start right up and idle fine. I push the throttle down and it seems like its not getting enough fuel almost like not all the pistons are firing. I stop for about 5 to 10 minutes then start and it start fine take off and again 1/2 mile or so it does it again. and surges. I thought it was fuel delivery. I tried different fuel cell. manual fuel pump. electric fuel pump. tried both fuel pumps at the same time and same problem. the fuel pumps work great. so I dont know what it could be. Right when it dies or start surging I stop and pop the hood. I check the fuel filter and and its full of fuel every time. IM stumped. what do you guys think.