have a 99 s80 t6 that's been doing some strange things. i have a surge while driving . no particular rpm, no particular speed and it's intermitint. i've been threw the usual like vacume leaks, coil packs, injectors, fuel pressure ect. sometimes i get a message immediate engine service required but no check engine ligh or no code set. sometimes the immediate engine service lights while this is happening, sometimes it doesn't. when it happens it feels like someone is pulling on the e-brake when i'm driving. pulling and letting go. other than that the car runs awsome. plenty of power, revs fine ect.
here's another strange one. while in gear but at a stop, if i press the gas pedal while holding the brake nothing happens. it doesn't rev against the brake. it's like depressing the gas pedal while the engine is off. absolutely nothing all the way to the floor. it's completely dead. take my foot off the brake and it works as it should taking off with no hessitation at all. it did this the other day. i tried it today and while standing and applied the brake and the gas both. this time it reved against the brake. i'm sure somehow this is related to my ghost surge issue. they are two very strange issue's. i've also heard when i take my foot off the brake a hiss sound every once and a while driving. can someone explain how it's possible to apply the brake and the gas and have it act like the gas pedal is not even connected? thanks... holloween is approaching.. hmmm.

Sounds like your ETM (Electronic Throttle Module) is dying. All '99-'01's had the defective ones that eventually do what you're describing (both of your problems). Take the car to the dealer. It is a warranted part now for 10years/200K miles and they should either do a software download to help the issue or replce your ETM.
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1998 S70 T5 Emarald Green Metallic (125K), 2004 V70 2.5T Ruby Red (45K), Previous Owner of Black '94 850 Turbo Wagon (Sold at 140K and miss her). My cars have been running so well lately they've got me worried.

thanks... your dead on! it finally threw a code. actually two codes for the throttle control module. i was thinking this am that perhaps the speed sensor is defective causing my hessitation and trans to shift early but then while on the x-way at 65 mph the car just shut off like the key was turned off. fortuneatly i was near a rest area and rolled in. when at the rest area the gas pedal didn't work. i would press it and it was as discribed before, nothing. as if the car wern't running. that's when it threw a code. i have all data at my shop and found that there is a service bulliten also. thank you for taking the time out to answer the post. much appreceated.

Just don't reset the codes. The dealer will need to see them to be convinced it's the ETM. If I were you, since the code came up and you've had numerous problems with this, insist that they replace the ETM...in other words, don't let them sugar coat the problem with a software download.
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1998 S70 T5 Emarald Green Metallic (125K), 2004 V70 2.5T Ruby Red (45K), Previous Owner of Black '94 850 Turbo Wagon (Sold at 140K and miss her). My cars have been running so well lately they've got me worried.