Did GM put RPM limiter in ECM to prevent too much engine RPM while in Park?

95 olds 88 royale has surging problems while driving with diminished response to throttle. I asked similar question just recently but now have another question. I have tried 2 different maf sensors with the same results. The original and a (reman like new) both make the rpm surge from approx. 5000 rpm back down to approx. 1500 rpm constantly up and down as long as I dare hold the throttle down. If I let up on the throttle to about 2/3 the engine levels out and runs smooth. Did Gm put a rev limiter in the ECM control module to prevent the rpm from going too high while in Park? My other GM vehicles do not react like this car does. I have changed almot everything except ECM. What about having the ECM reflashed?