98 Trooper overheating after intake manifold gasket and Plenum gasket

[rosebud]

I just had my intake manifold gasket and plenum gasket replaced because I had a check engine light and gas smell. After, whenever I go up a hill, my temperature gauge pegs at H. I have a new thermostat put in, thinking it was the gauge, but after a new thermostat, it still pegs at H temp on hills.

Has anyone ever seen this or have any suggestions on what it may be?

Rose