2001 V6 4.0 SOHC

Hard shift from 1st to 2nd gear SOMETIMES. Usually when I slow down to turn/yield/round-about then hit the gas. RPM’s go up, takes a sec as if it were in neutral, then shifts hard into second. I’ve learned to take my foot off the gas when I feel it’s going to hard shift, for a smooth transition. I’ve changed the speed sensor at the differential but no luck. Hoping there’s a couple other things I can try before having the trans checked. Any advice or experience with this issue?? Thanks in advance.

 

A common issue of aging 5r55e Transmissions; slipping due to worn ValveBody Gasket\Solenoids\ValveSeats.
How many miles on Vehicle+Tranny?
How long since a full Tranny service: PanDrop + New Filter + New PanGasket + New MerconV + BandAdjust, needed every 33kMiles\4yrs?
Make sure MerconV level is good?
I'd proceed as follows:
If level good but fluid is old, HandPump 1qt from Trans DipTube, refill with fresh MerconV; drive a few miles & repeat several times.
If that does not help, HandPump 1qt from Trans DipTube, refill with LucasTransmissionFix: LTF is just HiViscocity ATF to help it shift.
If that does not help, DropPan + New Filter + New PanGasket + New MerconV + BandAdjust.
If that does not help, a rebuilt ValveBody with New Solenoids+VBBondedGasket+ShiftKit; CentralValveBody\Donny in Oklahoma is a good source.
If that does not help, a new\rebuilt Tranny.

 

Thank you for the thorough breakdown.

 

Have we checked the fluid level? When was the last time the transmission was serviced with a new filter?