First off i have an 04 volvo s60 about 60k, just recently this week i noticed when i was driving over 70km and and over 2500 rpm the car would start to shake felt like id be going over a bunch of small pot holes felt like a whole bunch of vibrating, when i would slow down it would be fine, then yester day check engine light came on and it said engine system service required, then later on that day another light came on reduced engine performance and i couldnt even accelerate i would push the gas down and nothin would happen, i would have to stop the start turn it off then start it again and it would drive. now today same thing happened and it happening more frequently. i bringing it into the dealer next week. Any idea on what the problem is and how i can fix it.
the only recent change was i changed the oil to synthetic. last wknd.
please help

 

You need to have someone pull the codes out of the computer.