symptoms of faulty auto transmission

Hello,
What symptoms would an auto tranny that is low or has dirty fluid give?
I've got a 99 Silverado 5.3 that is acting up intermittenly, and just curious to know what symptoms of bad tranny would be.
thanks in advance!

the only way transmission fluid is low is if you have a leak somewhere. either way it would shift poor and have problems going into reverse. the low reverse drum needs higher pressure weather your going forward or reverse it takes more pressure to get that big truck moving. if the fluid is real dirty while your truck is on pull the dipstick. if there is bubbles then the filter is really clogged. i just had that problem with a 99 blazer.