Hello. We have a 2001 Silverado 2500HD with the 8.1 V8 in to. Lately we have had a sputtering no start problem. Almost like its vapor locked. We have cleaned the throttle body, replaced the Mass Air Flow sensor for the cold air intake, replaced the fuel filter, changed the oil and all spark plugs and wires. We are at an impasse and could use some pointers on what to look at next. I do have a video of what its doing.