01 Camry running rough

My 2001 Toyota Camry had an oil change and 80,000 mile checkup and drove home fine. We went out of town in someone else’s car the next day for the weekend. Driving to work Mon, it began shuddering and the RPM needle was waving quickly between 0.5 & 1.5 rpm. This only continued to happen when my foot was off the gas, especially when stopping. It drove fine when accelerating & higher than 45 mph. I took it back to the mechanic and & said he found that the solenoid had gone bad & affected the idle, & also that with the solenoid not working my spark plugs had been burned. He changed it all out, and it works ok now for me, but my wife had a day a week later when it vibrated when she drove over 60mph. I used it today and had no problem.
Is that likely that the solenoid would go bad w/out warning and affect the idle & spark plugs that way? Should I take it somewhere else?

@Dan4K

Did your mechanic scan for any fault codes when you brought it back?

I’m imagining you had a crank sensor code or a random misfire code . . .

“he found that the solenoid had gone bad . . .”

Please elaborate

Does he mean the idle air control solenoid?

BTW . . . what engine do you have?

Did your mechanic use the correct NGK or Denso spark plugs?

Have your plug wires been replaced yet?

2 common problems: Ignition coil and an egr valve. We need to know if there were codes. Was the check engine light flashing? And Idle Air Control valve wouldn’t cause any problem when the car isn’t idling, say driving 60 mph. And IAC valve isn’t common on these. If there are no codes, and it’s idling rough and low, an easy test is to whack, or rap on the egr valve with a hammer. If the diaphram is sticking, it’ll release and smooth right out. If the car won’t start unless your foot is pressing the gas, that’s the easiest way to pin-point the IAC valve. But, these are all guesses. The 01 Camry has 2 coils: One that fires cyl 1&4 and one that fires 2&3. If you have misfire codes for say 2&3, a good guess is a bad coil. If it’s a p0300 (random misfire) or a snigle cylinder, you need to check the FACTS. Fuel (prob good pressure and injectors) Air (no vacuum leak, prob good, unless your EGR diapragm is stuck open, causing a leak?), Compression (prob good since it’s intermittant), Timing (hmm…did your t-belt jump a tooth?), and Spark (as I mentioned: coil, plugs wires, plugs) We need more info.

Oh yeah, is it a v6 or a 4 cyl? That’ll change the ignition diag!!

I have a V-6 Camry.
He changed the EGR Solenoid.
My mechanic didn’t say if he scanned for any fault codes, or which kind of spark plugs he replaced with.
There’ve been no problems starting the entire time. It hasn’t stopped running either.

If it idles rough, I would clean the MAF and IAC. He probably cleaned the EGR, but I would call and ask.