[c1huang]

My car is a 98 alty, auto tranny. When I stop at a light, sometimes the car stalls. Other times is comes really close to stalling, the rpms dip down below 500 and jump up again. Also when I'm driving at any speed, sometimes the car just jerks back and forth, the rpms also dip down. I've taken it to the dealer but they said no trouble codes have been tripped. Could this be a bad spark plug? Or maybe I gapped the spark plugs too far?

 

[kenshi]

What kind of plugs and what are they gapped at?

 

[c1huang]

I think they're AC delco copper. And I think they're gapped at .6? I have a jacobs ignition so they told me to gap it a little higher.

 

[c1huang]

sorry I meant the gap is at .06

 

[AltyJae93]

I have had the same problem w/ my alty as well , when I am in in red light it stalls or sometimes the Alty shakes and Rpm's are falling. And I found out that it was the fuel injectors , there were struggling to give off fuel , so I took it to my mechanic and he first thing he told me was to try to use a fuel injector cleaner and that solved the issue .
So I hope this some help ......

 

[P/.\NTHER]

I had that same problem till I changed the fuel filter. Its a easy and cheap fix to do. Also try a fuel injector cleaner too.

 

[c1huang]

Hey Altyj and panther, did you get the same problem with the sudden jerk while the car was moving? I'm concerned that its more than a fuel injector/fuel filter problem, cuz the rpms drop when I'm also driving and all speeds including freeway speeds.

 

[dj_moshun]

Glad someone posted this thread. I have been having the same problem off and on. When my car starts (anytime of day), it shakes like crazy and the rpm's flux up and down until I give it some gas. Is this also a fuel injector problem or spark plugs?

 

[kenshi]

Glad someone posted this thread. I have been having the same problem off and on. When my car starts (anytime of day), it shakes like crazy and the rpm's flux up and down until I give it some gas. Is this also a fuel injector problem or spark plugs?

To me your problem sounds like something electrical like plugs, but c1huang's problem sounds like fuel system.