Spark plugs fouling

I have a 98 DOHC with 144k. Spark plugs appear to have carbon built up after 300 miles. Starts up fine when cold but wants to stall when warm. If it does stall I have to hold the gas pedal to floor inorder to start. Is this an EGR valve sticking open?

Replaced the temperature sensor, no more fouling of plugs

Thanks for the update - appreciate it. !!