Suddenly my green dot <acronym title="transmission">trans
</acronym> is having difficulty shifting from second to third. The engine revs up and will shift if I let up on the throttle or if I let it rev. I had a transmission shop repair a shift shaft leak 4k miles ago and it was working fine until now. I checked the fluid level which was high and there were some bubbles on the dipstick which made me think it was cavitating. I drained 8oz of atf out, which put it at the proper level. I replaced the modulation valve and made sure the vacuum hose was in good shape (even put a zip tie clamp on the hose). Now I’ve drained 16oz and added “Bar’s leaks” additive that says it will improve shifting. Nothing has helped. Should I pull the transmission and rebuild it or could it be the torque converter?
I appreciate any and all ideas.