I have a JD la150. First off the motor won't start unless I unhook one the coils. Doesn't matter which one. They both get spark. Runs fine if I have one of them unhooked but when I do that the mower won't shut off when I turn the keyswitch off. I have to cut the gas supply off to cut it off. I installed two new coils and new plugs. Any help would be appreciated.

Does this machine have a 26 HP Briggs?  
 
And when you "un-hook the coils", does that mean remove the black kill wire, the spark wire, or??

My toro timecutter did this and I put a push button kill button it
Easier than tracing all of the wiring harness