1990 LS 4dr:

my idle is bouncing and i've tried all of these
Cleaned the IVAC
replaced the FITV
tried a new distributor
new wires and spark plugs
coolant is ok
NEW 02 sensor

Throwing code 43, sometime when i hit the gas the tach will go right to zero, no power, today was the first time the car stalled. At normal idle where it's should be at 750 it is bouncing at 1-1.5k, at high idles it does some sharp bouncing, i kinda compare it to Allen iVerson dribbling a basketball.
I'm going to be replacing the fuel filter next, but beyond that i'm stumped, nor to good with electrics or spelling for that matter.

pls anyone this would be great.

 

ttt