99 Tahoe, Timing, Help!!!

Hello everyone,
I just replaced the intake manifold gasket in my 1999 chev Tahoe. Everything looks great except the timing. I somehow seated the distributor wrong and now the timimn is off. I tried taking the distributor out and turning the gear just a hair, reinstalling it and starting it.
I went from not starting at all to running rough and running OK but with a distinctive ticking that sounded like the valves we hitting the valve cover. Each try got better.
unfortunately my final try put me back to square one. Turning the gear again made it worse and now it will not start at all no matter what I do.

Do anyone know how to time a 1999 chevrolet Tahoe? Or an online resource where I can get help?

Help please.

Get the motor to TDC on compression stroke of cylinder #1.
Remove distributor cap, the rotor should be pointing at a pointer on the distributor cap base(there should be two of these V shaped pointers one has a 6 on it and the one you want has an 8 on it)
If it don't point at the pointer turn the distributor so it does, if you can't turn it far enough, you're probably a tooth off.
Find someone with a good OBD2 scantool to do the final timing adjustment- getting the cam retard to read 0 degrees, if you're more than 12 or so degrees(+/-) out your SES will probably light up with a P1345 code

Thanks for the help. I'm totally lost though. Furthur more I'm Sitting in my garage at home and can't go anywhere. Easier solution anyone? A web site with diagrams + direstions or something. Please, am in desperation mode

Thanks JeremyWI,
My truck is running now. I just have to get it to a shop to have it hooked up to a computer. It bak fires whenever I suddenly floor it.
quick question. Can bad timimg ruin my engine, or should I say how much time do I have to get ti timed right?

i'd get it done soon as i could...but if you cant keep eye on your temp guage..don't let it over heat...and gas ml. because you will notice that it's using more gas than it was..good luck...