96...transmission trouble?

I have a 96 Achieva SC, for the last few days when my car shifts from 1st to 2nd gear the car shudders. It had been doing that between 2nd and 3rd too, but that has stopped. We tried running seafoam through it, but still no change...any ideas?:headshake

Get it scanned on a trans capable scanner to look at solenoid functions and slippage errors, adaptive shift codes, for a proper diagnosis