Simpson

what causes idle hunting, idling between 1200 and 1000, also car always has some bucking while driving at 30 mph, or city driving

ander0e3

iTrader: (1)

How do your AFR numbers look? Have you checked your O2 sensor? I believe the new O2 sensor that I installed with my cooler thermostat and rad fan switch fixed my short lived idle hunting/bucking issue a few years back.

-Colin

mazdaverx713b

iTrader: (91)

Lets start with this. What year is your car? Any recent repairs or other known issues? Sounds to me without knowing the previous info, that its a throttle position sensor that's misadjusted or failing.

lduley

iTrader: (1)

I agree, or a new vacuum leak from said recent repairs

spooldr

textbook vaccuum leak, unfortunately there are a ton of sources. Best bet is to use a fogger to find the culprit.