Engine won't heat up

I have a 1998 2.7 4x4 extended cab. I recently removed a little vortex generator that was supposed to help with gas efficiency and right after I took that little unit out the engine will not get close to operating temp. If I let is sit and warm up it is fine, the engine temp gauge goes right where it always does and everything works. However as soon as I start to drive it cools down quickly until the gauge reads nothing and the vent air cools down significantly. What in the world is going on?

Welcome to the AF!

Sounds like you need a new engine thermostat.

I would also replace the thermostat.

Clifton