Temp gauge and gas gauge not working

If the gas gauge does not work correctly and the temp gauge reads hot, you could have a problem with the instrument panel.
Both gauges get power from the same circuit, but each gauge is grounded by its own sending unit.
If the temp gauge is reading correctly, you could have air in the cooling system and it is not actually full of liquid coolant.

you have a GM common problem and that is a bad intake manifold gasket. GM change the gaskets to plastic and they crank and leak causing over heating. here is a picture of one i took from a 2005 pon. bonneville with 74,000 miles on it

Code 102 is for a problem with the mass air flow meter circuit.
The sensor is saying the air flow is very low.
Could be the sensor or a leak in the hose between the sensor and the intake.

It could be a fuel issue or an air issue. There are so many different things it could be based on the symptoms. I would start with the fuel filter, if it contains trash it will restrict the flow of fuel to the engine especilly at higher RPM's when the engine need's it. Also, if the injectors are dirty they could restrict fuel also. If you have a leak in the intake manifold this would cause erratic running at higher RPM's also. Sometimes they are installed incorrectly. You can check this by letting the engine idle, have someone lightly press the accelerator (while it's in park of course) while you either spray ether or if you smoke, you can blow smoke into the engine bay near the intake and see if it's sucking the smoke up from some other spot rather than where it should be. Basically something foggy so you can see it being vacuumed from a leaky spot. This will even let you know if you have a vacuum leak. If all else fails try adding two small bottles of Lucas to your gas tank. It works wonders! Worth a shot.

it may be normal. did you bleed air out of the cooling system?

remember new head bolts also, torque to yeild bolts. i would recommend to get a service manual for torque specs and procidures for removal of heads. also head gaskets are leaking for a reason have heads checked for straightness and for cracks at local machine shop, keep all pushrods and rockers numbered for reassembly, pushpods are different and will cause major engine damage if mixed up.

Sounds like your head /intake gaskets are leaking better get system ckecked and compression test done soon .....It may cost more later

sounds like a leaking head gasket

head gasket does the overflow bootle have bubbles in it when idleing warm if does most likey rear head gasket.

sounds like you could have faulty gauges to meby check them out.... and yes its posible that its pluged