Black smoke '86 wagon 5.0L

Dad's Delta 88 Custom Cruiser ie the "War Wagon" is acting funny and I just need an affirmation of what I will have to do. Haven't got a round tuit on the electric choke but I can start it and go. Since I had a friend put in a transmission (pump in an overdrive quit pumping!) I can drive the silly thing but as it warms up it starts running rough and acts like there is a governer (sp?) on it and I can't accelerate past 35 MPH and as I push the pedal down, black smoke comes out the tailpipe but it doesn't blow out. I know it needs a tune-up and possibly a new float and filter. I've had the exhaust checked for restrictions but none were found. Could a baffle in the muffler be loose too? Any input would be appreciated!

:banghead: :screwy: