Jeep grand Cherokee , 2004 v8, transmission slipping code P0935

Question

My jeep tranny starts slipping after being driven about an hour, had mech check it out. He dropped the pan, no metal etc. but tranny fluid was over filled by 2 1/2 qrts. He put the right amount in, and some cleaner. Put it back together, now code P0935 comes up ? It's still slipping pretty bad, intermittent on slipping. I'm no mechanic, was married to one for 14 yrs. I like to fix what I can, my daughters BF owns his own shop. He charges me full price etc. I'm on SSI, can't afford $ for mechanic . Only had this car almost 3 yrs, had 2 other same model , year etc. never had tranny probs. this one has been nothing but probs. HELP ! I maybe a female, but I like working on my own cars. Thank you !