Ok. For the past 4 months I've had issues in the shifting of my '95 850 sedan with automatic trans. The car has 106K and I am the 2nd owner. I bought the car with 90K on it and some history. I did a major service which included flushing the trans fluid. All was well until about 98K when I noticed it shifting roughly between 4th and 5th gear no matter how I drove. I reflushed and all was well for a 1000 miles or so. It then started having shifting problems where it would try hunting for the shift points when driving from a full stop. Some days it was OK, others, I never knew if I was going to make it down the street. I then took it to a trans shop I trusted and they said the trans was OK but that codes showed that there was a bad speed sensor and the PRNDL switch was bad too. That too helped for a short while and the trans shop is at a loss because now the problem is intermittent and no more codes have appeared. My independent mechanic also looked at it and said it could be one of three solenoids inside the trans pan, but that would be an expensive hunt and search for the problem. Also, anything above 70 mph causes it to want to try and down shift like I'm passing someone. Sorry for the long post, but I don't know what else to do. Other than this problem, it is a wonderful car. Can anyone think of anything else?

Thanks in advance.