I believe 93 was the first year for the "E" electronic trannys. Yours should have come with the 700R4/4L60, not a "turbo" TH400 which is a 3 speed.
Your problem may be the mechanical kickdown adjustment on the TBI for passing gear. I'm not too sure about the older versions so just take a look and see if there is another cable on the TBI that goes to the tranny.
Here is a pretty good link for basic tranny info.