Miss at 4000+ RPM ECM code 43

My daughter's (new) 1991 Cutlass (3.1 L engine) runs fine at idle and low speed, but has a very bad miss over 4000 RPM. The Service engine light stays on, and a check of the codes reveals "43 (elec. spark control) People I got the car from just had a few ignition modules replaced, O2 sensors, plugs and wires by their mechanic- problem still occurs.
I replaced Catalytic converter (was plugged) / New plugs and new wires installed (found one of the mechanic's specials completely broken off in back of engine) The car still runs bad! PLEASE HELP!!!!!!!

After extensive research, the problem turned out to be a shorted Knock Sensor. The short occured after heating up, and would advance timing 15Deg. and car would miss.

Thanks for the info. Glad it was that and not an ecm.

Could the 89 2.3 QUAD 4 GM motor have the same results ( If having a knock sensor) , I did notice a long while back , Just as my water pump went out in my Calais , It would act really weird in the 4k-5k range. I was at the time street racing it , Had a few modifications put in it and then one day just acted weird right at 4k , Like skipped fire or bogged out , Dunno but lost at least half of the bhp and the torque decreased dramatically and acceleration was at like 5% of normal. Any suggestions ? Could be something to do with a loose timing chain to ( so i've heard. ) we'll see after I get mine retimed.

does any one know how to take a module out of a 1987 cutlas ciera gt