Timing Question again

[90'5.0 Conv]

Ok, heres the deal. About 2 weeks ago I finally advanced my timing from stock to 13*.
Boy, what a difference, throttle response was excellent. I then took it out to the track that same evening expecting the same throttle response and maybe a bit bettter time. Well, I drove to the track and my first real (WOT) stomp resulted in something unexpected, no throttle response whatsoever, lost what I had I guess so I checked my timing again and it was still at 13*. What the hell! I then commenced to further playing with my timing and today took it all the way up to 18* and that same performance I had initially was lost. Help me find it please. Did my cpu possibly do something to adjust, if so how do I get it back like I had it (13* with the noticeable throttle response). Here is a list of all my mods (lol). Gutted cats, ford racing plug wires, 2 ch. flows,smog pump elimination belt, oh yeah and TYPE R racing sticker. LOL Also for your info I just did a tuneup about month and a half ago. Thanks fo your help
James

------------------
90 5.0 Convertible
and loving every minute
of it!!