2001 Honda Passport and sometimes the check engine light flashes but other times it does not?

A flashing check engine light indicates a "catalyst damaging" misfire. Do not drive while light is flashing. It can(or already has) cause damage to your catalytic converter which can be very expensive to replace. It is likely you have an ignition problem on one cylinder. Bad coil or wire or something like that. It is not uncommon for that to be an intermittent problem. Your check engine light only flashes when it detects the misfire is present at that time. The regular check engine light will remain on to remind you there is a problem that needs addressed.