[MR2] MK2 running cold

[kevin smith]

My MK2 runs too cold and I'd like to fix it.

The real symptom is that the car takes a long time to warm up (during which it only lets me have 1/2 boost pressure) and when cruising the temp is only a notch or two above cold. 

I blame the fact that I no longer have the two plastic sheets
that go under the car below the radiator. I have been calling theses the air dam but I'm not sure that's the right term. They are the two plastic sheets that bolt on under the car in the front and together span the width of the car. I took them off when doing some work and they didn't go back well so I omitted them and I've since lost them. Could the lack of them explain the symptoms? (I always thought the thermostat would compensate by limiting the coolant flow) 

Where would I get new ones? I don't think the local pick and pull has any MK2s.

-Kevin