water should not be moving through the rad until the therm opens, the fld should be all the way up to the top of the rad before when the cap is off and should start over flowing the same time as it heats up. Nuke is the fld all the way to the top of the rad neck when you open it when cold ? the water should more fast when the term opens.

2001 5sp. K&N stock filter 215/70/15
If your check engine light is on at least you know the light still works