Hey. I've got this annoying/dangerous problem with my car and I don't know what it is and what is causing it. I don't really know how to simply explain it, so I'll just explain what the car does. This happens in any gear at idle. I'm just sitting at a stoplight, and all of a sudden, my car sorta lurches forward, and have to fully apply the brakes to keep the car stopped. The tach shows the RPMS jumping around, ~100 RPMs. It does this completely at random, in park, drive, or wahtever at idle. I installed an open air element this week, and I can tell sorta what it does when it happens. I can hear the "sucking" sound the car makes when it first starts, but it's at random and in sync with the surging. The car is a '92 RS 305 TBI. Thanks for your help.

 

all I can think of is that you have some kind of vacuum line damaged or disconnected

Its hard as **** tracing them though, good luck

-=-Mike

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1989 RS.. Newly installed 350,bored out 30 over, Hypereutectic pistons, double roller cam, double roller timing chain, accel wires, blue streak cap and rotor, rapidfire plugs, chevy caprice 350 chip, 200* fan switch.

 

If the car has a vacuum leak, it will run rough and shake. If you are not sure, yank a vacuum line off the TBI. If that changes it dramatically, more likely you have a TBI issue. I had this same thing, and it turned out to be a bad TPS. $25 and all fixed. I also took the IAC out and cleaned it and it's port on the TB. Hope this helps.