94 corvette rough split second stutter /shake
 

Hey everyone I have a 96 corvette with 105k miles, It is my daily it runs really well. Although I have a concern when at a stoplight holding the brake I’m getting a rough split second shake/ stutter every 5-15 seconds. When I put it in park or turn the ac on it goes away and idles perfectly


I have replaced the battery, starter, spark plugs “just plugs”, fuel pump and filter along with a fuel
pressure regulator

Any advice would be so helpful! Thanks

Have you scanned for any codes yet.

hey no codes are showing

I'm wondering if you may have something going on with the transmission, maybe?

Just spit balling ideas, but wonder if the increased RPM due to the A/C being on covers up a idle/no load misfire or vac leak that is always there. Been through a ton of this on my "barn fresh" 50K mile 88 unfortunately.Guessing that if you slightly power brake it while in gear it is fine?

Have you put a vac gauge on it to see what it says? My entire evap system had all sorts of leaks in the old rubber hoses. Other random ideas are fuel pressure and IAC counts, normal C4 stuff.
If your looking to dive deep in, Moats and Tuner Pro are a great (and affordable) combo for looking at/changing info and just plain getting data. Helped me a ton after being used to OBD2 vehicles! 'ALDU1 and CABL1' [ALDU1_CABL1] - $80.00 : Moates.Net

The vacuum brake booster could also be an issue, if it's leaking

It’s weird one day it doesn’t do it and the next it will…

Thanks for the help !! I will keep you all updated!

so at a red light or stop sign mostly at red lights when I’m sitting for more than 30 seconds to 1 minutes it does it during that time span.

I don’t know too much about the Evap system I will definitely look into it. Thanks so much!

Don't overlook MAF sensor or IAC. Cheap enough to clean and/or change if they are original. Known problems for later C4's.But it does sound like a vacuum leak.

okay thanks so much I will definitely start with cleaning and checking everything tomorrow