Solved it! TM Allison's suggestion that I swap the transducers - duh, why didn't I do that when I was fooling with things the first time?! - got me thinking. Checked and sure enough my '99 uses the exact same transducer to operate the EGR valve. Drove over last night, cleared the codes, swapped my transducer into the '97 and that fixed it. Ordered a new transducer this morning.

The best part was having my friend get in an drive it. He's had it for more than a year and never known how it should run. PO told him the CEL was a problem with the computer that didn't impact performance, so he just thought they were all that slow! Now you can floor it and it winds right up to redline and snaps through all the gears as it should! Not too bad for a non-turbo car (I'm spoiled with my chipped '99.) Of course it's back in limp mode until the new part gets here tomorrow. He's like a kid waiting for Christmas morning.

Simple fix, just took me awhile to get my problem solving sorted out. Thanks all!