i have a 52" scag walk behind and i had to buy a new engine for it 18 horse power kohler command cv493t pull start. when i first put it on it fired right up let it run for a bit and then mowed the yard for about 20 minutes. let it sit for a few days tried to start and had to pull for about five minutes before it would start. runs great when it finally starts. changed plug still the same, checked the ignition module to kohler specs sais its good, not any of the safety devices, checked all of those, key switch is good any suggestions could the ignition module still be bad. anyone have this problem thanks