1997 Bonneville SSEi "Shudders." TC or Misfire?

[Estabrooks]

Here's the "short" of it:

I have a '97 SSEi with 225K miles on it.

When I start heading up a hill in OD the car "shudders"/vibrates sharply up front until I downshift or I accelerate and it downhifts on its own. Then it smooths out. I read on the 'net that if, while it's "shuddering" you tap the brake, and it smooths out, then it's definitely the TC.

OK. It tried that test. It smoothed out when brake applied.

So I had a used trans. (150k mi. on it) put in it. No change. Still shudders starting up a hill.

Then I found this forum and read, the experience-derived posts by willwren/Zilla that the problem is most likely a misfire issue. So yesterday I had all the plugs and wires replaced. No (very little?) change.

What next? Replace the coil packs?

(I realize the used trans. could have the same problem, but it seems less likely.)

Thanks, in advance, for your help/advice.

[myfirstbonnie]

Did you put new TC in with the transmission?

Before buying coils, test them. There is a write up in Techinfo.

[reb]

I just paid $50 at the JY for a complete bracket with the 3 coils and ICM off a low mileage car. Brought my ohm meter and gave the coils a cursory test before paying.