Thanks to SIMPLESOUND for helping me with the car over the weekend. I now have the fuel lines and fuel rail insulated with Cool Tape. I had a little extra tape so I also insulated the underside of the intake.

http://i293.photobucket.com/albums/m.../IMG_13581.jpg

Your gonna like this!!!! I changed my fuel pump,fuel filter,fuel cap,the screen at the inlet of the fuel pump and tested almost all components with no fix for the vapor locking.Mt car has never done this before ever! So I looked back at what I have changed and also what I could do to change the temp by 20 degrees.When I replaced the clutch I removed the heat shield because so many of the bolts sheared off.My shifter rod was getting very hot and there was a lot of heat in the cab of the car coming from the shifter area.So I re-installed the heat shields and am no longer cooking the car via the exhaust pipe and cats! The shifter rod is cool now and there is no heat exchange coming from the shifter boot area.I figure the exhaust was heating up the trans and exchanging heat to the housing along with exhaust heat.That was enough to boil the fuel when it was really hot out.Oh yea I also changed my cap and rotor.No stumble now at higher rpms.The car pulls hard all the way to redline.Saaaawheeeeeee!

It vapor locked again.....My car has a jumper hose that links the return line with the fuel sending line at the firewall.I checked it and found a motorcycle jet inside of it.A 42 to be exact.WTF? I linked the lines back to stock and I will keep you posted on the issue.

That is a farely common "fix" for leaking injectors. Mazdatrix Version

My car hasn't vapor locked since after the insulation. I'm still getting pressure in the fuel tank though. I'm hoping that I quit having problems when I replace the cat.

Vapor lock
 

I also notice a lot of pressure when I go to release the gas cap it vents with enough pressure to blow up a balloon, is that normal?

That jet was in there sideways and made my car have hard starts when it was hot.After i pulled the hose and jet off,I plugged the lines and now it starts before I can turn the key all the way.I drove it in the heat in town for deliveries and it ran great.I think that since the jet spun sideways the fuel pump couldnt build pressure properly.

I'm currently experiencing these same symptoms on my GSLSE. I've done a lot of trouble shooting and no luck. However, what i've notice is that this issue usually occurs when it's hot outside. The only way i can get the car moving and performing properly, is to relieve the gas cap from the tank! What you guys think?

I was never completely able to figure it out. It seems to be very common with GSL-SEs.

It does only happen when it is really hot out and usually in heavy traffic. Whenever it has happened to me, if I open the hood there is a lot of heat under there. I did replace the cat with a high flow one and I'm hoping that helps move the heat away from the engine quicker.

Pressure in the gas tank does build up on my car as well. I haven't been able to figure out why. The breather hose on my car is clear. I would think the breather would let out all the pressure.

pressure in the tank is normal, unless of course excessive as in the case of an evaporative emissions system malfunction.

this is just a note so that people don't immediately think there is a problem when there may not be.

True. I wasn't thinking about that when I posted.

In the winter, the car does have a normal amount of pressure. When it is over 90deg and in traffic, if you pull the gas cap, it will have some serious pressure and will continue to blow fumes for over 5 minutes. You can also feel the air moving through the fuel lines if you put your hand on the rubber lines by the firewall.

the easy test to verify if tank pressure is causing a vapor lock condition due to overpressurization or a weak pump is to just leave the cap loose temporarily for a test drive.