Usually only happens after long trips of an hour or so, but i'll go from half throttle to part throttle and be in the -5hg to -10hg range of vacuum on the boost gauge and the car will very minutely stumble and then the accelerator kind of feels heavy and acceleration heavy, until of course I apply more pressure to say half throttle.

It doesn't happen all the time, but again seems to be mostly on longer trips cross country.

(NOTE: it only seems to do it during the summer: Happened last summer, then didn't notice it all winter, then boom warmer weather and it happens again. It was doing it last night, pre heavy rainstorm so very pressurized atmosphere in the 60's deg. F.)

(( Its always "Stumble first" then "throttle hesitation" so being on boost, to being around -5hg))

Not sure if its the BPV sticking or not letting out the pressure, I'm going to install the Forge BPV to see it that cures it.

Last year I had the same problem and I told the dealer to check the Purge solenoids, they ran check cycles on both the front and rear and said they were performing fine. I also had done the leak test by blowing in the front one and it did NOT leak.

Any input is appreciated if you had this problem or cured it?

Also seems like the car hates the rain and very heavy atmosphere weather. I also seem to notice it sometime stumbles when below a half tank of fuel.

Thanks

 

clean the throttle plate with carb cleaner making sure to clean the hinges also. then shoot the hinges with wd40, move it back and forth, wipe it off, and you will probably be good to go. the throttle plate likes to stick when it gets gunked up.

Why does this happen? here's my theory: If it sticks, the throttle position sensor is not in sync with the throttle plate causing the ecu to deliver the improper amount of fuel.

 

I read on some LNF solstice boards that they don't have a big problem with build up on the butterfly as non-direct injected engines do. Guy said he has 45k on odo with pretty clean. Plus i'd be weary of the Throttle by wire system. Some also said not to move the plate as it would interfere with the TPS sensor.

Its so odd that the car only does it in the summer. Also torrential rain yesterday and the MAF was bone dry. I added some tape foam above the headlights to help direct rain. So I know its not water related.

 

Did cleaning your throttle body help? I'm having the same issue.