Need some 700R4 advice

[Texasupton1]

I have a stock '83 305 that I just replaced the Qjet with a 500 CFM Edelbrock. THe engine runs great. However, with both carbs, we cant get it to downshift at full throttle. I thought it was just out of adjustment with the qjet, so when we put the Edelbrock on, with new TV linkages adjusted, it still wont drop down. Ideas??

While testing it, I noticed that the tranny was slipping a little between shifts.It was low on fluid, but after filling it, it still slips. It is fine off the line, pulls good, and shifts fine by hand, but there is a slip and a rev between gear changes. Any ideas?

Solenoid? It has set for about 3 years, would a fluid change and clean screen/filter help? Thank you.