I know there are alot of threads about stalling but it seems all the ones I could find were for TPI and TBI, so here's my predicament:
My car starts fine and will drive fine until after I drive it for about 30 minutes, or sometimes less in really thick traffic, it will start stalling out on me at stops and slowing down if I don't keep the RPM's higher. It'll get to a point that when I stop, I'll have to shift into "N" and that seems to help for awhile until it just gets worse and I have to let it sit for about 30 minutes before it'll run decently. When it's about to stall my temp is normal (approx. 180*), 10 psi oil, and idles at about 600 in gear. I do notice that there seems to be more than average heat coming from my 4" cowl hood scoop. It's where you can see the "wavy" heat coming up while at a stop and it gets pretty thick (if that makes any sense). After a while, my car will also start backfiring after driving it around and punching the gas. This all happens alot faster when I'm running hard. I've tried different adjustments with the mixtures screws and amount of air flowing to no avail. The plugs are new with a .45 gap. Thanks for any help.

 

Ide start with timing as timing can cause things to run hot and back fire. I assume this is a back fire in the intake? Next i would take a look at the color of your plugs.

 

I had the timing adjusted by a mechanic. It was 6-8* retarded, but after brain surgery we're up to 12* advanced. It was idling pretty smoothly in the shop, but now it runs worse. I can barely accelerate without it backfiring. If I let off the pedal while cruising it makes a gurgling, sputtering sound. The mechanic said that the valves are out of wack and are not closing properly. The big problem is, I bought this engine rebuilt and I'm not sure what cam they put in there. I know it's not a stock, crate cam - now I don't know what the valve lash should be. I'm pretty sure it's a performance cam with moderate lift, but I don't know the exact specs. Is there a way to find out without taking out the cam and/or is there a certain amount of lash that I can start with?