Question keeps stalling

[biotech]

i have a 2000 avalon xl. over the past few months the car's check light comes on and the car is impossible to keep running. the battery and alternator are fine. it might be the air intake. in any event, i'm at a loss as to how to proceed because, despite having road service twice, and the car towed twice, the service technicians can't seem to duplicate the problem. the car is serviced regularly and is up-to-date with all maintenance.
any advice would be appreciated.
thanks.

[ROKTOY829]

Can the shop not read a code? Sounds like it could be a e.g.r. valve or a i.a.c. valve problem.