1994 GMC Jimmy 1994 GMC Jimmy wont stay running

Hi, my name is steve, I have a 94 gmc jimmy sle with a 4.3L vortec 'w'engine. I'm currently having a problem with keeping the truck running, every time I step on the gas I lose complete power almost like im losing fuel pressure, so far the spider injector where replaced 10,000 miles ago, I have replaced the fuel pump, the fuel sending unit, the fuel filter, the fuel pressure regulator, the o2 sensor and still no luck, the truck had 2 engine codes, a code for the egr valve and a m.A.P. Code. I put the truck in the shop and the mechanic found 3 vacuum leaks in the truck, two in the mapping system and one from the egr, he repaired them which cleared the codes, and I know he didnt just wipe the codes from the computer because I disconnected the battery to make sure, so as of right now when I start the truck it idles fine for about five minutes, then if I step on the gas it completely dies and white smoke comes out of the exhaust, I have no engine codes and im at a loss, could anyone please help me out