I have recently started having an issue with engine roughness when driving on the highway at speeds of 55-65 when I go to accelerate at those speeds I notice a lack of power and roughness and also during that time I also get that rotten sulfur smell. I have suspected for a while that a coil pack may be going bad but due to no CEL i'm not sure which one because at idle it seems fine. If I am at low speed and accelerate hard it has no problems with power. One other thing I have noticed is that when coming to a stop the rpm's will go down to 500 and feel rough but go back to normal but it only does that during a sudden stop which around here is alot due to construction. I have just within the past 2 weeks been getting a CEL of P0442: Evaporative Emission Control System Leak Detected (small leak) which from what i've read points to the J hose which I do plan to do soon but from what i've read should not affect driveability of the car which i'm not sure is true or not.

I recently had to replace my catalytic converter again due to the aftermarket one being poorly manufactured and would blow exhaust gaskets. This time I got an OEM one and put new 02 sensors in.

Any ideas or suggestions ?

 

Should have checked timestamp before replying but....
As an idea plug in reader and check how spark advance is operating.
When engine was warm if I revved the engine and then let it return to Idle it would run rough and sometimes cut out. Also occurred when just about to park up after driving for about 20 miles.
Other indications I had was vacuum was high at Idle if I blipped the throttle. This would also cause CEML to flash up.
Above idle consumption was good, running at speed was good. Acceleration was also reasonable.
I have just been through a long list of replacements of parts on my v70 2.4 petrol.
Replaced camshaft position solenoid this morning. Vastly improved (but possibly still not quite there as now have intermittent error code regrading timing advancement - will do a few more miles to see if this settles down) .
Would also suggest if you are unfamiliar with some of the readings shown on your plug in diagnostics that you have a look at "schrodinger's box fuel trim" if you do a quick search - helped me to an idea of what some of the readings actually meant and might at least eliminate some areas not worth looking at - would have saved me replacing the fuel pump!!!! Still it is fun.
Although I should know better I have probably replaced parts that didn't need doing but as my intention is to get at least another 100,000 out of the car currently at 162k miles) I am hoping it is money well spent as car was cheap in the first place.
Sorry to waffle on but hope that this helps someone at least.