My 94 ls has been stalling recently. It still runs strong but idles very slightly rough at times and then stalls if it sits for more than a few seconds. It has an underdrive pulley, adjustable cam gears, intake, and exaust. All mods have been on the car for over 3yrs and dyno tuned. I have cleaned the air filter and replaced the fuel filter. It ran great for a couple days after each but then resumed its old habits(I'm thinking it did that because I unhooked the batery each time). The most likely things that I can think of are the fuel pump, EGR valve, and vacume leak. If you know where the EGR valve is please fill me in. What do you think is wrong?

 

probably the fuel pump had the same problem