Bought a 91 z28 L98 and it has red top injectors. I think these are 30lb. I checked the chip and it looks to be stock. I'm have a studder problem after warm up with some stalling and a smell of gas. But ONLY after warm up. Otherwise it runs great! Problem is at it's worse right of idle with light gas pedal movement. Any help would be great thank you.

 

Red top fords sounds like 30#hr. Does the memcal still have the Anjf or aujp sticker over the chips window ?
Do you know why it would have such large injectors. Cam / head change ?
looks like you might have two choices. Get it tuned or swap to 22#hr injector.

 

Just bought Saturday seller only mentioned it had a cat back. He had since 2016 never tagged it. Sat in garage. Does not have a chop to the idle though.

 

The sticker doesn’t look disturbed. I would guess it’s not tuned.
The best thing to do is put 2#hr injectors in it and see how it runs.
the 30s can probably be made to work with the flow setting changed in the tune and additional volumetric efficiency table work. But might not be worth the expense unless you tune yourself.