those tbi had a few issues to look at that could also be the culprit. while its running at idle have your while pan air cleaner assembly removed and physically look at the injectors spray pattern. it should be a nice clean cone. slowly open the throttle by hand and continue to watch the spray pattern to make sure it stays the same but the pulse speeds up. also look real close that you dont see drips of extra fuel at anytime during this visual test. also make sure you dont see any fuel coming out of the back of the tbi. if you see any of these issues its due for a tbi rebuild. the seals around the injectors can fail causing extra fuel to get dumped in especially at wot. if has been touched previously there's several things that can have been done incorrectly so be on the lookout for that. in the back half of the tbi is the fuel regulator. its just a spring operated diaphragm that can fail may not be visibly apparently besides the cone pattern gets crappy as you open the throttle blades.