2009 volvo S40 rpm's up from 3000 to 6000 without any gas acceleration. It will stay between 6000 and 7000 doing 65 mph without touching gas at all for a few second then drastically decrease in rpm's to 2000. The second day after purchasing this started and Volvo dealer states they can not reproduce s they will not trouble shoot. At times the rpm's will be at 4000 and the car goes into idle while driving. Any ideas ?

You most likely have water in the spark plug hole that is shorting out the coil pack. Pull the Coil Pack and dry it out and spray with WD40

ever do a tune up? full 60k miles listed tuneup.
id bet 90% chance that fixes it.

At a steady 65 mph, the torque converter clutch (TCC) is engaged. When you accelerate, the ECU disengages the TCC to gain extra torque for acceleration and then re-engages TCC when speed is steady. Its kind of like having an extra gear.

Here is the OBD2 emission system drive cycle test procedure.
Engine coolant temp must be below 70c (158f) before starting the engine for either the first or second trip
The fuel level should be less than 1/2 full
First trip:
Start engine, idle for at least 1.5 minutes
Drive 3 minutes, hold b/f schdl: 1.5-2.0 msec, selector lever "3rd" eng rpm 1,800-2,000 A/C switch:ON Hold the recommended b/f schdl range. Allow road speed to vary as necessary.
Drive at 55-65 mph for 1.5 min b/f schdl 2.0-3.2 msec, selector lever "5th" Engine rpm 2,200-3,000
IGN "off" for at least 10 seconds (not more than 5 min)
Dive at 50-60 mph for 3 minutes Selector lever "4th" keep engine speed above 3,000 rpm Allow speed to vary if necessary. Do not decelerate for more than 3 consecutive seconds. A/C switch ON.
Drive at a steady state cruise of 53-58mhp b/f schdl more than 1.8 msec selector lever "5th" eng rpm 2,400-2,600
Downshift to "4th" and decel more than 5 seconds without breaking, then idle for 1 minute.
Drive two minutes b/f schdl less than 2.0 msec Accelerate to 41 mph, decelerate to 34 mph, accelerate to 41mph. Do not completely release the accelerator. A/C switch off.
Idle 1 minute in park or neutral
Drive two minutes Steady state cruise at 31-44 mph. Selector lever "4th" A/C switch OFF. Hold the accelerator pedal as steady as possible. Allow speed to change if necessary.
End of first trip. Turn the key off the begin the second trip.
Second trip:
Start engine, idle for at least 1.5 minutes
Drive 3 minutes, hold b/f schdl: 1.5-2.0 msec, selector lever "3rd" eng rpm 1,800-2,000 A/C switch:ON Hold the recommended b/f schdl range. Allow road speed to vary as necessary.
Drive at 55-65 mph for 1.5 min b/f schdl 2.0-3.2 msec, selector lever "5th" Engine rpm 2,200-3,000
IGN "off" add four gallons of fuel
Dive at 50-60 mph for 3 minutes Selector lever "4th" keep engine speed above 3,000 rpm Allow speed to vary if necessary. Do not decelerate for more than 3 consecutive seconds. A/C switch ON.
Drive at a steady state cruise of 53-58mhp b/f schdl more than 1.8 msec selector lever "5th" eng rpm 2,400-2,600
Downshift to "4th" and decel more than 5 seconds without breaking, then idle for 1 minute.
Drive two minutes b/f schdl less than 2.0 msec Accelerate to 41 mph, decelerate to 34 mph, accelerate to 41mph. Do not completely release the accelerator. A/C switch off.
Idle 1 minute in park or neutral
Drive two minutes Steady state cruise at 31-44 mph. Selector lever "4th" A/C switch OFF. Hold the accelerator pedal as steady as possible. Allow speed to change if necessary. I especially like the part where they want you to add four gallons of fuel. Not three gallons, not five gallons, four gallons. Gotta love those Nissan engineers. ...and of course they state that if the trace is not followed exactly (i.e. you botch the acceleration/deceleration) you have to start all over again from scratch

Sounds like your transmisson is going, i had the same problem.

3500 is about normal for an xb at 65 mph. My previous ride was a pickup and rolled at about 2000-2500 on the highway. But the XB's engine is way more "tightly wound". Your rpm gage should run at about half of of your speed...ie: 70 mph will be about 35 (3500) rpm, 80 mph will be about 40 (4000) rpm. Freaked me out when I first got the thing, but after researching it Ive found out that with a stock engine it actually runs more efficient at the higher RPM's. The 06 boxes won't redline until 6000 rpm, so unless you are driving 120 on a frequent basis you're good. You can probably have it modified to run lower, but you will lose the awesome gas mileage and overall it is not going to improve the way it runs, and would have no benefit............

No....the rpms differ from engine to engine and from manufacturer to manufacturer. RPM's are always higher at higher speeds.

check for loose engine / trany mounts

it could be a motor mount check the condition of it or it can be that something with the suspension might need attention . . those things can cause vibration at certain speeds

one unit that operates ratio changes and is connected to the engine is that vacuum operated actuator on the transmission
it is possible that that unit is failing , vacuum hose is leaking and that will cause ratio changes as the vacuum varies
run the fault codes to check for wiring problems or VSS or TCM problems as well