2002 Chevy Blazer MISSFIRING

Hi, Kirk from St. Louis. I am sick of my fiance's 2002, chevy blazer extreme, 4.3 v6. It hasd 114,000 miless on it and the timing chain was just replaced. I also had the fuel pump replaced because after the timing chain was replaced the truck kept cutting off. The check engine light started flashing but the car was running fine. Soon after it starting abrubtly shutting off. I had it hook up to a diagnostic computer and got three trouble codes. 1. The crank chaft position sensor, the camshaft senser, and lastly it said that the fuel injectors were misfiring. Two of the injectors read like an auctioneer spitting out numbers, and the other four injectors all read different numbers. So, I replaced all the fuel injectors, had the check engine light and codes reset. The car ran fine for about 10 miles, we drove the car with the computer hooked up to it. The check engine light started flashing again, this time the computer read that the pistons were misfiring all except one and the car dies.