trans issues 98 ssei

just bought the car a week ago 90% of the time it shifts great sometimes shifting verry rough and going through the gears way to fast....sometimes its jerky on the interstate as if od kicking in and out today i jump in cold takes off great get 1.5 miles out and starts slipping the further the more it slips if you let it cool it does just fine again until 1 mile or so and repeats took to auto zone and read fault codes...p0440 evap (expected that one due to its age and milage 186000)...p0742..tcc stuck on(paper says) tcc comanded off by the ecm-tcc slip detected after off command...p1860..pwm solenoid electrical fault(paper says)..the ecm has deteced an improper voltage level on the tcc pwm solenoid circuit...im not stupid by far when it comes to working on cars but dont know where to start here if anyone could give me some insight here i would be forever in their debt...thanks in advance....oh btw....fluid level correct and not burnt up although slightly dirty...i have added sea foam to the fluid as i have read on the fourm here and what the heck does pwm stand for???

Unfortunately, you need to take the car to a transmission shop and have them diagnose it for you. It sounds like the transmission is bad but it could be a connection to the computer or a bad computer that is causing the issue. Unfortunately, unless someone specializes in transmissions it will be hard to diagnose and advise you on repairs. I suggest AAMCO as they will diagnose it for free.

pwm= Pulse Width Modulated

update....have a grinding noise in the bell housing area...any chance the torque converter or the input shaft could be striped it still drops in forward and reverce gears but slips when you give it fuel....thanks verry much for the previous and future repilys