It sounds like you have several issues.
The thottle position sensor could be one of them.
I would reallly worry more about the coolant problem as that seems to indicate that you might have a head gasket leak or a leak in the coolant system. I would suggest getting the coolant system pressure tested and find out where, if any, fluid is getting lost first.
Then I would have the fuel pressure checked. You might have a bad fuel pump or bad fuel pressure regulator that is causing the problem at idle.
If the fuel pressure checks out okay, then you might need to replace the idle air control valve, IACV. It controls the idle under cold starts like a choke and also under load when you turn accessories on so the engine idle remains the same whether it is cold or at operating tmeperature or if there is a load on the engine from accessories at idle or not. You may need to replace the IACV.
Thursday, November 1st, 2012 AT 1:56 PM