Intermittent ranger transmission p0750 5R55E shift solenoid

Question

Recently bought 2002 ranger 4.0 with 5R55E. Throwing p0750 code. It was fleet vehicle must note it shifts awesome runs excellent. 97k miles. I can see the trans looks pretty clean looked closer look it is remanufactured looked up model it is a factory rebuild. I asked my local dealer they said warranty needs reciept... b.s.... but now its getting noticeable. The only problem really is the od light will flash and sometimes when cold I put in drive and it starts out like 2nd gear or thumps into gear. Same with reverse. I also notice with ac on freeway going 70mph it feels like the ac drag is extreme. It seems all electrical because the trans feels like new if that makes sense. One other thing to note is some fleet depts will buy a remanufactured trans and install it in house and not do any necessary pcm upgrades. When I bought it the battery was dead and tjey used a crazy jumper that really juiced it hard. The radio is shorty the volume goes up and down on its own and can't read the display on stereo very well. The oil pressure gauge was bouncing back and forth a lot for the first week I had it. And it had no symptoms for 10 days after I bought it. These issues have been progressing for a month now. I am going to ford dealer to ask them to do what they think considering the mechanical components seem to be fine. I will pay to have them repair it right I have learned my lesson transmission shops are mostly priced comparable to the dealer but easy stuff seems to be over priced at dealer especially on touchy transmissions l will pay a little more for integrity of a dealer if the problem reappears I will more ap to believe dealer.