I had pure hell with the kit for ATX like Tempo. '94 model rebuilt and the kit put in but it did some wonky stuff like goofy timed shifts and some really hard. Like dropping a clutch. The downshift into low gear at like 50 mph at trailing throttle is what really did it, locking wheels up there. Yanked kit after looking again super close to make sure I did nothing wrong. Car then proceeded to shift perfectly with no kit in it. Huh??
Had both '88 and '94 Tempos, looking through the evolution of VB mods in stock parts vs. the kit changes I realized many of the shift kit mods were already done on the '94, which from factory shifted much better than the '88 ever did. Problem was, some were not, thinking Ford did some slightly different plate hole sizes or springs, or something of that nature not easy to find. So, how much of the kit do you do? I did it all but skipped anything obviously already done since redundant, like a hole that should be so and so size, pull this spring out, etc. I DID change any spring supplied since you can't look at it and tell the value there. Some of them point that stuff out in 'where to stop steps' out but this one did not and clearly said on box for 'early' ATX, thinking that was the kicker. Still have the kit in case I ever try to put it in the '88 model, which shuttle-shifted way too much even brand new.
It could easily be that I put a stronger spring in something that Ford cured by making bore bigger or something like that while keeping same value spring. Meaning maybe a mod on top of a mod, just done a different way. Didn't have the million dollars for research to find out the small difference there.