i dont know if this makes a difference but before all those problems started i noticed that the engine temp gauge wasnt working correctly, it would go up a bit when i drive but when i stop for awhile it would go back down to cold. also the fuel mileage went down alot lower...

 

The coolant temp thing sounds like a stuck thermostat. When the car is moving and the engine is producing more heat you're ok but then when you stop the thermostat stays stuck open. This could also be impacting your gas mileage because the engine is more efficient at the proper operating temperature. I very much doubt that's related to the bucking/loss of power you're feeling though.

 

check the hose down by the turbo under the air filter for a tear. IF it's the cause look for a silicone type (they seem to last longer)