Chevrolet Repair: 89 CHEVY SCOTTSDALE, throttle position sensor, fuel pressure regulator

Question
I have a 1989 chevy scottsdale 2wd truck.  About a year ago a 350 motor was put in.  Recently, I ran it and it was fine then the next time i got in it was hard to start, had to put pedal to floor to start.  Now it just putters, if you accelerate real fast it seems to rev up ok, but when doing it slow it just acts like it wants to quit.  It is smoking alot now and you can smell a real rich gas smell. Only thing i have done is change spark plugs, doesnt seem to help, and i have heard the fuel pump running, any suggestions would be appreciated, thanks.  

Answer
1989 should have a TBI. There are a couple of things that it could be. One thing is the fuel pressure regulator. If you know how to check the pressure it should be running somewhere around 13 to 20 psi. Another thing that could cause is is the throttle position sensor. Also about the only other thing it could be is the O2 sensors. The things you need to check for are the things that control air and fuel flow. Without being there to look at it I can't be exactly sure yet what the problem is but this is a good starting point. If none of those things are it then get back to me with a follow up and we will go from there.