Temp Light Comes On And Temp Gauge Drops To Cold. Then Go Back To Normal. Not Over Heating

no
if the thermostat is not opening , the temp will go up until it hits the red and stay there
possible a blocked radiator core not passing enough coolant at rpm
check for transmission not moving to overdrive
run fault codes

Sounds like the thermostat is sticking, on warm up on lot of vehicle the gauge goes past normal and when the thermostat opens drops back. If it is going higher than normal, the thermostat is opening late. Needs changing before it stops opening altogether.

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.

Did you bleed the air from the system? That must be done or the system developed air blocks and this causes it to run hot.

i had something similar once, it ended up being the intake radiator hose, it has a metal coil inside, mine was broken and when you revved the motor it would **** the hose shut and overheat, but under 2000 rpm it was fine .

Sounds like a stuck thermostat

Sounds Like A Problem With your thermostat. Good Luck

try skewing the engine coolant temperature sensor with a multi-meter and a temp vs resistance or voltage chart. the ect could be out of range and not set a code. also check actual engine temp with an infrared thermometer. hope this helps

Sounds like faulty engine temp sensor. When it drops to cold, the engine control unit picks this up and alters the fuel mixture accordingly. The ECU will be making it a very rich fuel mixture for cold starting, hence very poor running when engine is hot.

TL

Hondas are famous for this, my accord does it. This is normal UNLESS it still idles high after normal running temp. has occured. Watch your temp. gauge when it reaches normal temp tap the gas a little bit if the idle drops then it is fine