Struggled with this for years. 408, with TTI and TKO 600, RobbMC starter. Starter and header in area of starter is heat wrapped. Did not help. Battery in trunk so 20 feet of cable. Did some voltage loss checks and found battery not getting 12v to starter. This lower voltage fine for cold starter but not for hot starter. Added 1/0 cable, largest I could find and this fixed it. Now, it still struggles a bit if i am driving around town in hot weather, but it has never let me down since.
Is your battery in front/back and what is your cable size and voltage loss to starter?
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