Sometimes all those owners shown on Carfax reports can be the same person reported multiple times, for example if a parent gifts the car to a child it's technically a title change. Another example would be if the car was originally leased and the lessee decided to buy it at lease end... It's the same person but Carfax reports it as a 2nd owner.
I was gonna bring this up. I used to do DMV work and this came up every once in a while. It looks like the vehicle has been pawned off from owner to owner, but what may have happened is
1) Someone leased it brand new.
2) They bought out their lease and transferred to their own name
3) They decided to add their wife/husband to the title
4) After it had accrued a few miles, they decided to give it to their high school graduate,
5) They legitimately sold it private party
That's just one example. But those will all show up as different owners on a Carfax, as I recall. DMV considers them actual ownership transfers every time.
HOWEVER, if it were me, I would check (as mentioned above) for a cold start misfire, make sure there's not Block Seal in the coolant reservoir/radiator, ensure that it still goes in/out of 4HI and 4LO with ease, have a mechanic check it out, etc. etc. etc.