Engine problem
2001 Lexus ES 300 6 cyl Front Wheel Drive Automatic 103000 miles

For the first time in owning this problem has surfaced:
After two cold (20 degrees) days of non-use, vehicle did not start immediately; had to depress and hold accelerator for vehicle to start.
New battery was purchased, cables cleaned, but problem has persisted intermittently.
Auto has original wires but all spark plugs were changed 30000 miles ago and front spark plugs cleaned 5000 miles ago.
New platinum plugs will now be installed.
Is it time to change all wires (front and rear)?
Should gas filter be changed as well?

Thanks for your assistance.