2000 Century TCC issue

2000 Century with 80,000 miles. On a recent road trip, the Service Engine Soon light came on while at freeway speed. Also the transmission began shifting up or down with a hard jerk. I stopped, hoping that turning it off for a while would clear the problem, and checked oil, trans fluid etc, nothing leaking, not overheating, so we pressed on taking it easy since there was no place to have it looked at. For another 100 or so miles this went on. After parking it overnight, the next day, the jerking had stopped, but the SES light remained on. We only drove a short distance then parked it again overnight. The next day all was well. we drove home with no trouble. Since I have a ODBII scanner, I hooked it ip and got a P0742 code. TCC stuck on.
Question to anyone experienced in this area: Can I expect to see this again? Is it necessary to replace the TCC. Can it be done without removing the transmission?

the 4T60-E and the 4T65-E,,,,it's ether/or has had problems with valve spools in the valve-body,, forces inside cause the valve to side-load,,causing them to stick,leak,or hang....Sometimes an additive like
"Lub-Guard" will lessen the problem,,,but valve replacement is the cure.
Sonnax sells great replacement valves

I looked around for the Lub-Guard you suggested but did not specifically find it.
Could you be speaking about one of these "Lubeguard" products?
1. http://www.getautohelp.com/automotive_products/62005.html
2. http://www.getautohelp.com/automotive_products/61910.html
3. http://www.getautohelp.com/automotive_products/60902.html
If so - which one? 1, 2, or 3?