would a bad spark plug be a reason why i have trouble startin up my truck when its warm

 

It could be one of the many reasons.

 

Its possible, but it sure wouldn't be the first place I'd look! Think about it... one spark plug out the 8 stopping the engine from starting?!! It would be more likely if all the spark plugs are bad and it needs a complete ignition tune-up. That would be a good place to start.

The next things I would look at after the ignition system are the 02 sensor, ECT sensor, and IAC. Then I'd look at the the fuel injection system.