th350 shift problem

I have an 85 Monte Carlo with a mild built 350, 282 cam, edelbrock carb and intake with headers. The car had not been driven much when I bought it the engine and trans (built th350 w/b&m shift kit) only had about 10 to 15k miles on it. The trans shifted great for a short while then began having problems downshifting back into 1st at stops when left in drive (does fine manually) and was holding gears too long before shifting up. We removed the govenor and found some trash it in causing it to stick, fluid looked good so we cleaned it and that fixed the upshift problem. Still wont go into 1st at stops unless I manually engage it and when I put it back into D it short shifts second basically goes 1-3.:confused:
Any help would be appreciated.

where is the governor located at? anytihng that may help solve tihs prolbem is worth trying before buyign a new tranny.

thanks

it is located drivers side of tranny back by the tailhousing has a big cap that covers it with a bar that locks the cap down. I'm thinking possibly trash in the valve body causing a solenoid to be sticking but me and my biz partner both have limited knowledge once we get past the basics.