Irratic RPMs.....help

while driving...usualy 30 to 40 mph....my RPMs will jump around irratically from 1000 Rpms to 3000 RPMs within a split second and jerk the car until i let off the gas.....1993 lumina euro (sensors?..tests?.....HELP!!) thanks

Check the car for codes, check Throttle Position Sensor, Idle Air Control motor, check sensors associated with tranny, all else fails, drive ur car on up to a GM or Chevy Dealer and have them check it out

i have a code 42....something with the DIS module.....im confused about this car

Mine used to do that. It would run fine for a few miles, then, it was as if the engine was being turned off and on again over and over at a steady pace. Car would buck, revs would jump. Floor it and sometimes it would go and the Check Eng Light would come on. Checked the codes and had 2. MAP High (max high value) and MAP Low. Went to replace the MAP sensor, found the plug "falling" off. The tab was broken and a tie wrap was holding it. Replaced the tie wrap, the plug is now tight, it runs fine. Just a loose plug, poor electrical connections. (The dealer wanted to replce the fuel injectors.)

In a Previous Post, in an other thread, i messed with my idle screw and reset the ECM, and with tinkering with it, ive got it at where it idles at 1000 perfect...now dont ask me how but i removed the fuse for ECM, messed with the idle screw, turn it up a bit, and turned the car on. And Drove away Best Idle Relearn i ever did lol. I drove it for awhile, started to idle at 800 so i turned the screw up now its at 1000 so fiddle with it, maybe it i'll help. IT HELPED ME A BUNCH Good Luck