HELP Won't shift to 2nd unless off the gas
 

My ol 2002 z28 camaro automatic, won't shift into 2nd unless off the gas , transmission fluid is good and still has color , when it does shift it shifts fine with no clunking. Is this early signs of the transmission going out? Or is there a bad sensor somewhere? Anyone else had similar problems? Any information helps. It's my only vehicle right now

Need more info like is the shift being commanded and then note happening or is it not being commanded, Where to start depends heavily on knowing this ,

There are no sensors involved. As Frank says, it is best to know if the shift is being commanded.
However, since a tune does not change by itself and from the age of the car, I suspect your band is starting to slip.
You can check this by pressing in on the servo cover with e.g. a crow bar and estimating how much it moved. 1/16-1/8" is good, 3/16" is marginal and 1/4" is where the band starts to slip.
Also check the fluid level which is best done with the engine running. (I find that with the engine off for a while, a fluid level 1" above the "Full" line is a good approximation of being full.)