14 sierra 4.3l rpm bouncing

[Michael Wheeler]

Ive got 14 sierra with 65,000 miles. Bought it with 53,000 miles from dealer. When driving down the road in drive or m5 at almost any speed but mostly around 40-55mph let off the gas and the rpm needle drops down below 1000rpm then starts bouncing from 1000rpm to 1500rpm over and over. Still Coasting and Foot still off the gas eventually it will go back into gear and u can feel it. Does this 90% of the time. No codes pop up. Ive brought it to dealer and they said nothing is wrong. Also has shitty shifts. Anyone run into this problem and figure a fix? Gonna try dropping tranny pan and replacing filter soon.

[Inacanyon]

Where’s your oil level on the dipstick?

[Jmott]

Mine also does this when it drops cylinders, as soon as I out my foot back on the gas it stops. It is odd and annoying. 

[Grumpy Bear]

On 3/4/2020 at 8:25 AM, Michael Wheeler said:

Ive got 14 sierra with 65,000 miles. Bought it with 53,000 miles from dealer. When driving down the road in drive or m5 at almost any speed but mostly around 40-55mph let off the gas and the rpm needle drops down below 1000rpm then starts bouncing from 1000rpm to 1500rpm over and over. Still Coasting and Foot still off the gas eventually it will go back into gear and u can feel it. Does this 90% of the time. No codes pop up. I've brought it to dealer and they said nothing is wrong. Also has shitty shifts. Anyone run into this problem and figure a fix? Gonna try dropping tranny pan and replacing filter soon.

Your dealer is right. That isn't in and out of gear. That's the converter locking up and freewheeling. Your *****y shifts are a slight amount of programed slip between gears to protect the unit and soften shifts. IF you want  it to feel like a TH-350 talk to Black Bear. IN the mean time change the fluid and filter and do those that ask for further information attempting to help you the courtesy of a reply.