In my early 20's, the only test I took, and really knew of, was the Humanmetrics one - would always get INTJ at that time.
Started getting mostly INFJ by my mid-20's, but have gotten all INxx's at one time or another.
With the cognitive processes test, I got ISFP once, INFJ once, but otherwise I always get INFP, because my Fi tests higher on that test than Ni does (but they're basically a tie), and Fe is usually in the bottom 3-4, with Ne in the top 3.
A socionics test I took resulted in 'inconclusive' INFx, but when I answered a final question to break the tie, they then said I was INFp. So, probably either one w/ socionics too. ;-)