99 tahoe Missing at idle and check engine light on

I need help big time. My truck recently overheated and I took it to Firestone and got a new Water Pump installed. Since then my truck has hard miss at idle..and my check engine light is on again..but when driving it's fine but my check engine light remains on. I took it back to firestone and the tech told me I needed a Major tune up which he replaced 4305 Platinum plugs and distributor Cab and ignition wires and a fuel system tune up....still my check engine light is on and I still have a hard miss at idle. Took my truck back to firestone and he informed me that I needed Fule injectors...so the tech replaced #4 injector becuase it was miss firing and he also replaced Fule injectors 6, 8, 5, 7 and from what he told me it's still miss firing 4 and 6. At this point I don't now what to do. I spent close to 1,000 so far. Can someone help me. I'm taking my truck to a chevy dealer this weekend but I'm thinking they will tell me the same thing. Please help. If this sounds unclear I don't now much about trucks...... Please e-mail me at RKTownsend@mybluelight.com


Thanks
RTownsend

How bad did the truck overheat? Is it running hot at all now? If the problem started at the time of the overheat then they are more than likely related. You could have blown a head gasket or something along those lines. Take it to the dealer they should be able to diagnose the problem for you.