My ES 300 has 123,000 miles, hadn't drove it since Christmas & ran fine then, today I started to drive it & the CEL light & VSC light came on & it has a rough idle, I pulled the code & it says code 1354, mfg. ignition control or a misfire, dosen't say which cylinder or bank, I can erase code & it will clear up & run better for a little while but the same problem returns. What should I look at first ? Thanks