I have a 1999 Silverado 5.3 Z71 automatic. The other day driving home the truck infront of me stopped to turn when I put my foot in the brake my truck down shifted funny. When I gave it some gas to go up a hill it felt like it was trying to shift up/down shift. I thought it going to stall out. I put my foot a little more into the throttle and it drove fine. Went out a couple hours later and it died when I put it in reverse. It seemed to idle odd in gear but not in park or neutral. I changed the fuel pump and fuel filter. Went to town and it seemed fine til I got around 45. It didn't act like it wanted to shift. Slowed down to turn and it down shifted funny again. When I turned it acted like it was in neutral. Got to where I was going turned into parking spot it died when I put it in reverse to park better. Went in came out would die when put in reverse and forward. I put my foot on the throttle and put it in reverse and it went. Got home pulled into spot left it in 3rd for a sec or two and it tried to lurch forward with my foot on the brake. Sorry for the long post. Any help would be appreciated

 

this might help it might not but on my other truck i had the same issue except some times if i didnt hit the gas fast enough throttle wouldnt do anything. Did you run any codes my issue was a TPS Sensor.