Transmission issue shifting beyond 4th gear

Hello all! I've read quite a bit on here about others issues with the transmission not shifting beyond 4th, but I'm not sure anyone has posted the exact issue as me. I've replaced the shift solenoid twice now. I believe it's Solenoid D or S4. It seemed to work temporarily and wasn't a long term fix. I'm wondering if the problem lies somewhere else in transmission. I've others replaced the pressure solenoids. Both B and D at the same time and it worked. Is there another obvious fix I'm missing here?
It occasionally resets when I turn the truck on and off, but it can take 3 or 4 cycles while I'm coasting in neutral and it's getting old! I have 308,000 miles on it and dont want to get rid of her yet just because of the transmission.

Thanks in advance!