6elements

i have an 01 automatic teg. ive done an oil change, distributor, spark plugs, and o2 sensor.

my problem still exists. what happens!! my car seems to surge power when im on the freeway. i dont feel it on stop and go streets. ALTHOUGH!!!! when im on a nice straight away, i will feel the car surge, or hesitate, or feel like its gonna stall. i've done the recent tuneups listed and still i have the problem. i do have a DTC which is generic P0455. """""gross evap leak""""" i've checked every hose leading to this DAMN object and found nothing. even tried thick soapy water SPRAYED over the evap lines to find leak!!! and still no progess. ive been under tha car from the gas tank to the intake maifold and evap cannister. still no leak. note: car is on while i spray spoapy water on it so i can see any forming bubbles.

conditions....

normal operating temp
car would "surge" and as i step on the throttle, i get no response.
RPM will not rise, but will drop slowly.
when i stop, the engine would stall as if there is no fuel or the car has turned off.
restart car and it runs fine.

1/4 "quarter mile" and the car would do the same thing. this time, engine shakes violently. **not always**

restart, and car starts up fine and runs fine.

this is the most frustrating troubleshoot ever!!!!!!!!!!!!!!!!!!!!!

i have taken the cat off to look at. no tear or wear. everything looks nice inside the cat. no evidence of clogged cat.

Modifications
150k miles
cold air intake.
and BONE stock!! Excluding my fake *** intake. thanks in advance!! any help is appreciated.