Cal Trac Mono springs?

Can you wear these out?
Took our Demon out to No Problem raceway this weekend.
Great air & the 340 was making power.

First pass, the left front picked up 2 feet & the right rear squatted like it had stock 6-cylinder leaf springs.
It then went right, my Son corrected & continued down track.
The car stayed up on the left side, at least 6 inches, all the way down & was a hand full to drive.
It never settle back down.

Made 3 passes & adjusted everything we could, nothing changed the way it drove.
All 3 passes had 60ft times of 1.45.
The car was so ill handling down track, that we put it back on the trailer & came home.
Looked over for broken parts, check shocks, nothing helped.

We put an average of 500 passes a year on this car.
The Cal Trac stuff is going on 7 years old.
Can these springs get worn out?

It has been getting worse over the last two seasons, but havn't had any problems with hooking up or drive ability.
We did swap springs from side to side last season & it seemed better for awhile.

I'm sure the extra power it made over the weekend, it showed up worse than at other times.
Open to suggestions.