1995 G20 Trans trouble

i have a 1995 chevy G20 cargo van w/4.3 and auto trans. It started shifting out of OD and not down shifting into first gear at stop. I replaced A&B solenoids, new filter and fluid, still no change! At the same time this all started to happen the motor is running real rich (black smoke)????????
HELP!!!!!!!!!

i have a 1995 chevy G20 cargo van w/4.3 and auto trans. It started shifting out of OD and not down shifting into first gear at stop. I replaced A&B solenoids, new filter and fluid, still no change! At the same time this all started to happen the motor is running real rich (black smoke)????????
HELP!!!!!!!!!

You need to fix engine running problems first,
Engine has to be running good for transmission to shift right.

Fuel pressure?
Last tune up?
Any codes or check engine lights?
Is the TPS sensor good or throwing a code?