I started noticing when I first go to start up my car the engine revs for longer than normal before it turns over. The starter was replaced 2 months ago with a brand new one. I also checked the air system to make sure it's good, cleaned the maf and changed the filter. I have done all major maintenance including timing belt and water pump. Any suggestions will be greatly appreciated.

Will update you with results.

 

Vacuum line, O2 sensors,
You could do a smoke test. You checked spark plugs, right?
(I have the same problem with the GS300)