Toyota: 87 Camry 48mph Chug

I've got a 1987 Camry 4-cylinder with 158,000 miles on it. Automatic
trans. I'm hoping to get another 100k out of the car.
It has been running great but has developed a mysterious lurch in the
46-50mph range. Runs otherwise with power and seems to shift smoothly.
However, when entering the 46-50 mph range, especially on deceleration, it
will lurch noticeably. The local shop has checked it out and says that
nothing is wrong but it's still a little worrying. Also a little slow off
the block sometimes.
I'm considering replacing the oxygen sensor as a first try. Another
possbility is the torque converter solenoid which is supposed to kick in
about this speed.
All feed back is appreciated.

"John" <com.au> wrote in message
news:3f47ebae$comindico.com.au... 
been 

You have had this going on for a long time? It seems that it's just become
very noticeable. However, we went on a 200 mile trip last weekend and the
car performed flawlessly. Maybe we will tune it up and not worry about it.
Thanks for the replies.