hey i have a problem with my 97 dodge ram 4x4. it burn a qt 150miles ish. its drives great but when i slow down to a stop the rpm guage drop quarter inch then goes back to regular idle. i also have a oil problem! it dont leak not 1 bit of coolant or oil. i looked down throttle body was not clean had alittle bit of oil on sides. i noticed i had 1 drop of oil on end of exhaust. my thoughts are pcv or the intake gasket is leaking into exhaust. Please help me decide what to replace.