This issue is on an 85 Cutlass, stock 3.8 V6 about 132,*** miles on it with auto transmission. It just randomly started today. Car from stop will go no problem, but then will not upshift intermittently. Seems to get stuck in 1st or 2nd. Then will be fine...then a little while later, will happen again. No transmission leaks, fresh transmission fluid about 500 miles ago with fresh transmission filter. Again it's not consistent, just intermittent. The car does have hydraulic suspension, and I checked to make sure nothing leaking out of my output shaft seal and nada. Ideas of where to start and what to check? Oh and its the stock 3 speed transmission. Thank you for your time.
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