Savett

Good morning fellas I have a problem with my L 98 motor. I'm fouling out spark plug on number 4 cylinder. the car only has 50.000 miles on it it .runs 14 in a quarter so I think the motors in good shape.does not consume any oil.i think its valve seals.the motor is a 90 vett

Injuneer

Unfortunately, you posted in the LS1 Tech forum, which if for the engines used in the 1998-2002 F-Bodys. I'll move your post to the L98/3rd Gen forum.

Assuming you are still running the stock multi-point fuel injection, could be a problem with a leaking injector.