Low pitch hum
 

Hello, I am driving a 98 Mazda b4k. When I am driving at higher speeds around 45+ and slow down or stop there are times where I get this low pitched hum. Sounds like its coming from my throttle body. Also there is oil spitting up out of my throttle plate into my intake and eventually getting on my air filter. Are these two related? Also when the humming starts I have to hit the gas kinda harder than I want an that seems to make it go away from time to time. Is my throttle getting stuck? Any help would be great as I am moving soon and driving my truck to new destination and I don't want this to pose a problem getting from here to there. Thank you in advance.

oh sorry when this happens I stall out sometimes.