. . . My question to you all is, do you know of any sure fire way to see if it has been tuned?
Should I just be safe and pop the stock intake back in or would that also cause problems if it was tuned?
I think it is safe to assume that it has been tuned, otherwise it probably would be throwing lean codes.
Two ways to tell for sure:
1) ask the prior owner (good luck with that)
2) have a Ford dealer check the CPU . . . they will charge about $100 for this, and they won't be able to tell you what adjustments were made in the tune, only that the ECU has been reflashed
Unfortunately this happens often, and it is bad behavior on behalf of both the prior owner and the dealer. The prior owner should have been more up front with the dealer about the tune, and provided the hand-held tuner with the car. The dealer should have noticed the modification and asked about it, and then handed that information on to you. Unfortunately these days very few people care about anyone but themselves, and each of them got their money and then they were done.
If you put in the stock intake with the adjusted tune, it will run rich. If it is running fine, I think you can leave it alone.
The reason that the JLT intake requires a tune, is that the MAF metering section tube is larger diameter than the stock tube. This throws off the Mass Air Flow sensor readings, and the tune needs to be adjusted to "recallibrate" it. If you change the tube diameter back to stock without recallibrating it again, it will be off in the other direction.
You should probably assume that it was tuned for 93 octane, and run 93 octane gas. I assume the dealer didn't tell you about that either.
This will also present a problem if you want to install future tunes, because you don't know what you already have. Any new tune "should" be installed on top of a known factory tune. One way to solve this, is to go back to stock; have a dealer install a stock tune; and start over. Also some tune writers might be able to get it straightened out for you.