Not suggesting you are NOT INTP Dave, but none of those reasons listed rule out ISTP. All are listed in Berens materials as fitting ISTPs - not sure if they also fit INTP (since I have only had the materials for a few days and haven't read up on everything). Ignore me if you've already come to a conclusion.
Would you say you are more Informing (INTP) or Directing (ISTP)?
"We are out of milk versus "Please buy some milk"
What about language? Are you more inclined to use concret pramatic languare or do you speak in a more abstract manner?
Other good info from Berens:
Sources of Confusion
Several descriptors used for iNtuiting misled these individuals to self-report on the MBTI® or self-select a preference for "N."
Big Picture - Many Artisans-SPs are interested in the big picture. They say they want all the detail, the whole story. One ESFP selected "spire" over "foundation," saying he saw himself on top of the spire seeing the whole picture.
Pattern - Likewise, most of these Artisans-SPs also indicate they look for patterns. Looking for patterns is different than perceiving the pattern first. The differentiating point is the starting place, not the ending place.
Extraverted Sensing and extraverted iNtuiting are holistic, analogic perceptual modes. In extraverted Sensing, the individual elements, like the trees in the forest, are seen in rich detail, all at once. Thus concrete patterns are quite likely to be perceived along with the discrete sensory information. This pattern is different from the abstract extraverted iNtuiting perception of the relationships and connections of the trees to the rest of the environment. Both pattern and big picture can be on a continuum from concrete to abstract.
Possibilities - These Artisans-SPs frequently respond to "possibilities" as an accurate descriptor. When we probed deeper, they described seeking opportunities for action, usually what to do next and what will work to solve a problem. They like brainstorming and coming up with variations on a theme, until the process goes on and on and on and gets too far away from reality. Those who prefer extraverted iNtuiting are increasingly excited by the ideas sparked in the process regardless of how far abstracted from reality. Both extraverted iNtuiting and extraverted Sensing focus in the here and now and on possibilities and opportunities. The differentiating factor is abstraction or concreteness.
Hypotheses
Type Pattern vs. Mental Process - To understand extraverted Sensing, we consult those who have S and P in their four letter code, asking them what they would do, listening to their words and observing their behaviors. We frequently fail to remember that in the _S_P type pattern (hierarchy of functions), there is also iNtuiting. For example, someone with ESTP as preferences, also has introverted iNtuiting. Even though it is in fourth place, it is there. Those with ISTP have introverted iNtuiting as tertiary (following Grant's model) and as adults, probably have had much opportunity to develop and use it. The functions do not operate in isolation, but in dynamic interaction. Could it be what looks like extraverted iNtuiting is really extraverted Sensing, with an introverted iNtuiting perception of the near future? Could this be the attraction to "big picture," "pattern" and "possibilities"?