Detonation after mail order tune

I ordered a SCT SF3 tuner with a custom 93 octane performance tune, and I have been running 93 for the last 5 tanks. Here's the deal - I loaded up the tune following the included instructions, then took her out for a spin. Under light throttle, the car felt much stronger to me, but once I gave it over 50% throttle, I could hear detonation, in all gears. Getting onto the highway, I couldn't get my car to go over 70 in 5th gear, and I could hear the detonation pretty clearly. Luckily had the presence of mind to bring the tuner with me on the trip, so I pulled off the highway and returned the car to stock, thereby eliminating the problem

My car is basically stock, with the exception of the PI intake (which I included on my mods list when ordering the tune). I'm pretty baffled as to how this mail order tune could be so far off. What could have gone wrong? The instructions said the battery should be disconnected on 94-97 mustangs to reset the keep alive memory, should I have done it as well even though mine is a '98? Should I request a new tune or go elsewhere? I was thinking I could modify the tune but I'm not comfortable playing with those parameters.

Thanks in advance for any advice

Thanks - I'll give them a call and see what I can get done

Well, the car is basically stock and was running fine without any sort of tune - I got the mail order tune only because I bundled the SCT tuner with my 4.10s and saved some money. Ideally, I'd like to dyno the car but in it's current state, it probably isn't worth it.

As far as engine damage - I don't feel any power drop after returning it to stock, still got 28mpg highway with my crappy 2.73s. Probably ok? I'll pull a plug this weekend to verify.

I know it's serious, which is why I pulled off the road to return to stock. I tried the new tune they sent me, it still sucks. Car is staying stock tuned until I can find a good dyno here in upstate NY.