Hey all sorry if this post should not be here but i didnt know where else to put it ok heres whats going on i have a 98 z28 ls1 6speed last night temps dropped to about 30-35 degrees at about 8 in the morning i went in the garage to crank up my z and once it started the rpm shot up then dropped to the point of almost stalling it was as if i had a Huge cam in it it kept doing that for about 20 seconds then the rpm shot up again i turned the car off and waited a minute and cranked her up again seemed to run fine i drove two blocks to my brothers house to pick him up and shifting was insane i felt like i could feel every little movment inside the trans when i shifted i wasnt shifting hard or anything well i sat at my brothers waited for the car to reach normal operating temo and checked trans all is good but still feels weird and also if i start driving and push down on the clutch to shift my rpm go up just a bit but its enough to notice not sure if this is normal i never had this happen and not sure what to do or not to do i have to take the z out of town in a week and really dont want to be stranded on the highway lol sorry for the run on sentence here thank you all in advance for any help

 

sounds like an idle air issue or something in that area...maybe a intake air temp sensor failing due to the cold. Just a few thoughts not great on the electrical side of a ls1

 

^^^either this, or, because of the cold, there is a gasket contraction or similar. I'd check the IAC grommet for looseness, vacuum lines, etc.

 

While you're at it, check the intake bolts to make sure they are not loose.

 

Thank you all im going to give it all a check tomorrow and see what i cant come up with i will post an update as soon as i know thanks again