Just picking some brains here? Just added a new header 6-1 and put on new exhaust. 1974 FJ55 1F. Ran fine down to the shop which bent the exhaust. Now she cuts out when warm. Initially back fired some. If you drive you can make it about 100' before stalls?i If u let idle it will idle fine for about 5-10 minutes then stall. Very confused. Redid the exhaust gasket(used metal one instead of cheap one with header) with a new one and the copper gasket stuff. Retorqued. Still stalls? Very frustrated. Also has new plugs, wires, battery cables. Any ideas out there?? I have had for 6 years and has always run strong until now? stuck in the garage in CO!