Gauges giving me trouble

The coolant thermostat is either stuck open or missing.

Both issues could be normal to a degree. The engine temp would go up some when the truck stops moving, and the oil pressure would go down some when the engine returns to idle.
Are the two gauges reading out of normal range ?

Possible bad sending unit or shorted sending unit wiring.

Duplicate question

Well it could be the sending unit for the gauge.
But odds are the oil pump or engine bearings are worn out.
As the engine warms up, the metal spaces expand and the oil gets thinner. The oil pressure drops some under normal conditions, but not more than 10 or 15psi. Normal idle pressure with the engine warmed up is probably 25psi.
You could check oil pressure with a mechanical gauge to make sure its not the sending unit.
Once the oil pressure starts staying below 20psi for long periods you'll start hearing noises.

If the engine is reaching normal temp, you would need to test the sensor on the intake and the gauge on the dash.
The sensor provides ground to the gauge.

The oil sensor sending unit is shot,

Hi,

The overheating and lack of cabin heat both point to a failed engine thermostat which would be stuck closed. At the warm up stage, the coolant stays in the engine block to bring the engine to efficient operating temperature, then it opens and circulates the coolant through the radiator and heat core. If the thermostat is stuck closed, the engine will overheat, and coolant will never reach the heater core, and you will not get cabin heat.

Blinking oil light at idle which goes away during driving could be a low oil level, but may also be a drop in oil pressue. You could have a clogged oil fliter (at best) pickup tube, or a failing oil pump.

Does the car have a normal oil level on the dipstick? The behavior is consistent with a broken timing belt except for the part about the temperature gauge going to the top which would indicate overheating or a faulty gauge.

Sounds like the thermostat may be sticking,Or the temp sensor is going out.Both very inexpensive.