1999 Chevy Tahoe engine timing

Timing your engine is not like the old days. Using a timing light will not work because the computer advances and retards the timing automaticaly. The timing must be set using a computer scan tool. The problem is that you need a very expensive scan tool to do this. It is best to take the Tahoe to the dealer to get it timed.
If the engine runs, DO NOT assume that the timing is correct. The timing of the engine also has a lot to do with the shift points of the transmission so, if the engine is not timed right the trans. Shift points will be off.
BTW does your engine have a distributer or does it have the coil over plug system?

If you are changing the distributer I suggest spending the money and put in an Accell distributer gear on your distributer. These gears are made of a harder metal than the stock (brass) gear, and you do not have to worry about it wearing out. The modification you heard about requires the engine to be removed. It is usually done during a rebuild, otherwise forget about it--it's not worth it.
The p1345 probably has to do with the timing being off. You are correct that it has to do with the cam sensor -- this code is common when the timing is off.
This will get you close to the right timing -- bring number 1 cylinder up to TDC on compression stroke. Take the distributer cap off -- the rotor should be pointing at the number 8 scribed on the base where the cap screws down to -- look close for the 8 because there is a 6 also scribed into the base but that is for a 6 cylinder. Adjust the distributer so the rotor is pointing at this 8.
This will get you close, but a trip to the dealer is a must. The code reader or scanner you need is called the GM TECH 2 or a Modis scanner. These scanners are not for the novis mechanic, they are for a dealer or a professional mechanic -- they cost around $8000.00. A trip to the dealer to get the timing right will cost around $40.00. But if you insist on timing it yourself then you have to invest in a GM TECH 2 scanner or a Modis scanner.