What is the thermostat rating on a 1999 Pontiac Gran Pri GT 3800

Should be in the line going into the accumulator.

if the engine is the same 3800 then yes

Follow the top radiator hose down. It will connect to the engine. At the point that it connects to the engine is where the thermostat is located. This thermostat cover will have two bolts. Some of the 3800 engines have a temp sensor in the housing. You will not have to mess with the sensor. The housing will have 2 bolts that hold it on. Remove the two bolts and the housing will lift off. And the thermostat will be under the housing. Replace the thermostat. And reinstall the housing.

you may have a bad sensor

Yes. Remove the housing (not the hose) and you'll find the thermostat.

When you lift the hood look at either side headlamps and see if you can see the bulb sockets/Twist the socket to remove the bulb and replace with similar bulb

Mine usually runs right smack in the middle. If it's middle or under you are fine. If it's over half way, then you need to change your thermostat, or you cooling fan isn't kicking on when it should. There is a temp sensor that controls the fan.

yes it could be. have fuel pump pressure tested, fuel pump pressure should be. (key on engine off) 1999 to 2000--with egr--41 to 47 psi without egr--52 to 58 psi,

you open door look at end of dash on pasenger side

**if the Eng 4 cylinder they are located under the coil bord which is on the top of the Eng tide with 4 bolt 13mm
*** if 6 cylinder they located under neath the valve cover or u can follow the spark plugs wire