The head has been damaged more than likely especially if it backfired after completing the job ...

What prompted the replacement of the timing components ?
Usually chains do not require service but the guides do.

The engine had not been opperating like it did. The gas milage was down to 15 miles per gallon from 20 and it has 230000 miles. From checking with others after replace parts from fuel filter to the idler and all part in between. Plus having a valve job done I felt that that would solve the problem. When I removed the time cover the tensioner was damaged and laying in the oil pan and the chain was loose with some wear on the gear teeth. So I did replace the timing componets and it backfired out of the exhaust when I started it. So I reset timing with #1 cylinder at top dead center and had a problem lining up the cam pully to match the chain to the crank and the marks on the tensioner. So I adjusted it to match. It fired up but it sounded like it was missing and then cut off. I thought it could be the camshaft sincer. But I also thought that the head gasket might have blown. Your thoughts could help me with a lot of time and money that I do not want to spend with all I've spent so far. Please advise me the best you can and I'll follow through with it, thanks.

your best bet would be to pull the valve cover and check for damage up top, then pull that timing cover off again .. if the marks where not lining up properly something wasnt right .. your timing is factory set off those marks and there positions do not change .. if you had a valve job done odds are something was missed or done incorrectly also which motor are we working with ( 2.2 SFI ) ? (4.3 Vortec) ?

Thanks for your responce. I had a friend that works on cars and after he started the truck and heard it he said that it was still out of time. He ask if I had move the crank shaft any and I told him that when the crank grear broke that all had shifted. He said that that would have to be adjusted cause it was still out of time. So hopefully he will fix it for me. So thanks again for your responce.