[donlee1085]

My replacement part came in this past Friday and swapped it out later the night. Job took me a little over 3 hours, given it was my first time taking off the air intake plenum and I was taking my time. The only part that took some time was taking the tubes off, other than that it was straight forward.

Thank you OP and others for the useful information, it made this job a lot easier than expected. So I would like to contribute to this thread as I’ve been experiencing symptoms for over a year prior to getting this part replaced.

Signs I experienced at the beginning:
-Bouncy idling, engine sometimes stalls/turns off.
-Gas cap light came on the dashboard, came on one morning then went away.
-SES light came on for increased emissions, which also would intermittently turn on and off over time.
-Smell of fuel inside the cabin.

My mechanic wasn’t able to figure the cause of the problems at first. He thought it could’ve been something with the ICV or A/C compressor, but no codes were popping up. At this time, he replaced both throttle actuators and all spark plugs. I was getting a TA code for bank 1, decided to get both of them done. There was a code was coming up for a coil, attempted to swap them out but then threw another code for a different cylinder. So with both TAs replaced, decided to keep an eye on it.

Months passed then these signs/symptoms were predominantly present:
-SES light STAYED on for increased emissions
-Smell of fuel inside the cabin was occurring more frequently
-At times, a notable noise could be heard during start-up, a vague *burnt* smell would be present for a few seconds inside the cabin.

Soon after a couple months later, it was THESE additional symptoms (to include the ones above) that I decided to start taking a look into:
-Engine runs rough during cold start up. I would need to give it a bit of gas in the beginning during the cold start. If not car will either stall or go into limp mode.
-Hesitation during acceleration, especially at WOT under 3-3.5K RPMs. Continuing to go WOT under 3.5K RPM will throw the car into limp mode.
-Decelerating while down shifting will cause the car go into limp mode.
-Cruising at a low speed (15-25mph in 2nd gear in a neighborhood, school zone, etc) would go to limp mode.
-Car SHUTS OFF completely when car is in neutral and getting out of gear, RPM drops straight to zero.
-Car stalls after fuel up. Would need to be on the gas, eventually the car will run on its own.

The issues were giving me a headache, had a diagnostic done when it was serviced for an oil change, 2 pages worth of codes were given to me by my mechanic, to include misfires on all 8 cylinders. He insisted on changing all my spark plugs and possibly my coils as well. ///M for money he noted lol.

So after a reset, gas cap light came back on followed by spontaneous engine stalls leading to limp mode. Restarted the car and SES light on the dash with less misfiring. Decided to drive it easy until I got these issue resolved.

One of the codes appeared was the DMTL pump. Did some research and decided to order the pump along an ODB2 scanner. Swapped out the part and cleared the codes. Ran fine for a day or two but then the gas cap light warning came followed by the other issues.

Decided to swap the gas cap. Ran codes prior to reset. What was 20+ codes narrowed down to 9.
-P0301-P0308, P0300 (misfiring in all cylinders)
-P0442 (small detection leak)

Did some investigation of the P0442 and lead me straight to this DIY. Very happy I was able to pin point the cause of my issues. Since I’ve replaced the part, noticeably difference between night and day. Thank everybody again for the useful information.