I've come across this twice this year.My 70 Chrysler 300 with a old MP conversion kit...every so often it would not start but would kick when i released the key.Changed nearly everything...still did it.Finally took the P4120505 control box and swapped it with a crusty used blue box...been mint ever since.Customer towed in his big block Charger a couple of weeks ago with the same problem.Put a new Chinese control box on and no issues since.20 or 25 years ago the orange boxes had a similar issue...run fine till they warmed up and then would quit
until they cooled down.