Also try pulling vacuum on the modulator and see if it holds. If it holds for several minutes it is probably fine. If it drops off quickly or you can't pull any vac at all it is bad. Adjusting it may also fix shifting problems if you don't have any other vac related issues.

I don't know if this goes for 126's but if you replace the modulator make sure you have the right plasitc pin that goes with it. I went through this (as have many others) on my 123. I had to switch from one that looked like this -------l=- to one that looked like this ------==. It made a world of difference.

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