tranny problem W163

[fugitivo]

I need help. I have a '99 ML 430 (107k). The transmission was completely destroyed (a bearing lost teeth which did a job on most of the parts) and I had it rebuilt by a reputable indy. Everything was fine for a couple of weeks, until Wednesday when I repeatedly experienced major slippage on the 3-4 or 4-5 shift when starting from a complete stop: it felt like the tranny was in neutral for a couple of seconds and the engine speed jumped 800-1000 rpm before the gear caught. It also seemed like when I tromped on the accelerator the tranny downshifted twice in succession (only happened once). The scary was one time when cruising at a constant speed of about 40 mph there was the "disengagement" and revving up for a few seconds. I returned it to the mechanic who has driven it for probably 70 miles without duplicating the symptoms. He has his computer hooked up to look for codes, but the only anomaly was with the rear sensors - one showed zero and the other much faster. He didn't think that was related, but wasn't sure. Has anyone got a clue?