transmission issue?

1996 SL2 automatic with 52,000 miles on it:

The car will only work in 3rd from a cold start and will work in drive when it runs for a minute. Took it to a mechanic and he serviced it and fixed the problem. A check engine light popped up and the car would not turn on in park and only in neutral with an error P0706 while the check engine light was on. Took it back to the same mechanic 2x and still got the same problem(a little over a month ago).

The car would also sometimes not shift while in Drive after the mechanic serviced it (would stay at 20mph while pressing on the gas).This happened 2x in one month.

I took the car to my mechanic and now it turns on in park. The check engine is not on either.

The problem now: The car will only work in 3rd from a cold start and will work in drive when it runs for a minute again.


Any suggestions or hints with what is going on is appreciated

John

You have probably already fixed this - or gotten rid of the car. I would have recommended that you have the "range sensor switch" on the backside of the transmission replaced. It the thing that prevent starting when in gear, and tells the electronic shift controller what gears you want to use. If it fails, the car would likel go into 'limp mode', where the trans would stay in 3rd all the time. But it should start out in first if you shift the lever to first, to get going. Then you could drive it in 3rd.
It also a hard place to reach and to work in!