Stalling out

I have a 1992 Chevy Suburban 4 wheel
drive 1500. After I change the
distributor cap and rotor I had a
problem when I put the firing order
back on but I got it correct it starts up
fine revs up fine. But once I put it in
gear it wants to die once I hit over 2000
RPMs maybe a little less actually
before hits 2000 it starts to die but if I
let go of the gas it'll stay on I don't have
to play with it it just stays on. But once
I try to give it gas it dies but if I
gradually pick up speed little by little I
can get going I can get up to 50 or 60
or faster. But tries to die out once
almost 2000 RPMs.  But if I let off the
gas it'll stay running fine. And to
actually get to 50 or 60 MPH it takes a
little bit bcuz I can't get it to 2000
RPMs. I did change the spark plugs
before I did the cap and rotor. I did
change the spark plug wires before I do
the cap and rotor meaning on another
date. I did change the fuel filter I
change the throttle position sensor. (I
think that's what its called) I also set
the timing to make sure it was right.
Now the scary thing is that every day
for the past week and a half if seems
to be getting worse and worse when I
drive it before I was able to actually
give it a little gas and pick up some
speed like to get on an on-ramp for on
a freeway. But now I wouldn't even
attempt it unless it's going downhill. So
the scary part was it's actually seeming
to get worse. Now I need help or
information on what it could be????