I have 99 toyota sienna. lately in the morning when i start the car it takes few trials to get it going. for the first few tials it turn off right after cranking. also i hear it is sucking a lot of air. i was told to check the idle sensor valve where is it. do i need to clean it or replace it. also i was told to check the coolant temp how to do this too.? already checked maf
thank you

fred50