O/d light

my 98 ranger od/ light is blinking and shifts hard took it to a tranny shop they rebuilt the tranny & replaced torque converter got truck back drove for a week got on highway o/d light blinking again took back to tranny shop he said truck needed good tune up to get a diagnostic reading tired of the excuses they give me.ready to take to another shop then sue 1st shop for bad work the ranger has a 4.0 v6 at 4wd any ideas?

Miles?
Codes?

the O/D light blinking means the Transmission Control Module has detected a fault. Did they tell you what the fault was? Can they even extract the codes? If the CEL is not on, a tune-up will not fix this either.

See if it’s the onboard computer. That can cause other problems too.