1996 Chevy Tahoe 02 sensor near front

First, take your truck to the dealer and tell the you want a crankshaft sensor relearn proceedure done. Also, have them check the timing - PROPERLY - and adjust it if needed. The timing on your engine CANNOT be checked with a timing light. It is computer controlled. Changing the crankshaft sensor requires a relearn proceedure to be done. Changing the cam sensor (sometimes) messes up the timeing.
It is impossible to tell whether an O2 sensor is bad by just looking at it. And they rarely, if ever go bad, without some sort of timing or fuel delivery issue--before hand--being the cause of failure. What are the exact codes you are getting?

Well, you really didn't say what the truck is doing other than mis-firing. The front O2 sensor -(or sensors - some engines have two front and two back)- regulates the fuel/oxygen mix into the engine. If this sensor reads too much or too little oxygen in the exhaust, it adjusts the fuel intake accordingly. Usually there is a mechanical issue with the fuel injector - fuel pressure - or spark plug and/or spark plug wires.     A miss in these engines can be very difficult if not impossible to find without a computer scanner like the ones a dealer has -- these scanners are not available to the public or other than chevy mechanics. All that being said your engine still operates on the basic 3 things   air - fuel - spark. Checking the obvious and common mechanical failures like spark plugs - wires - intake leaks or vaccume line off ETC. Is always the best place to start. Jumping ahead of the problem without following basic trouble shooting will result in you spending much more money than necessary -- like changing the cam and crankshaft sensors without testing them. Keep me posted.

Test the throttle position sensor or have tested for proper voltage rise and fall. Also, test the MAF sensor. Make sure your air filter is new.