Vapor lock means air is trapped in the fuel system and would normally occur only after vehicle has been stopped for some time.
The link explains how to go about checking for what is missing causing the non starting. Guessing is not going to work. When problem occurs whereby you are not able to start, you need to perform test to find out if it is ignition sparks or fuel pressure that is missing.
After verifying what is missing, then you can proceed to troubleshooting to locate the source.
Since manipulation of the throttle allows starting, the most likely cause would be the MAF. Try cleaning it and retest.
The injectors would be a likely suspect if they are leaking causing temporarily flooding and non starting.
Saturday, November 6th, 2010 AT 6:41 AM