Can you show me a diagram of where is the camshaft sensor on a 99 Tahoe?

If it's a V8 then it is on the left bottom side of the timing cover on the front of the engine. Behind the balancer. If it's a V6 then it is inside of the distributor, under the cap.

^ That's actually not correct. That is where the cranksensor is. The cam position sensor is in the distributor facing the firewall pointing sort of toward the driver.