Well thats kind of a hard one to diagnose with all those many factors. One thing i can help you with is the EGR problem...is the light still on? Well who cares if the light is on you got 154k on your car so you need to do this anyways with a V6 engine. Go to your local parts store i prefer advance and get 1 liter of seafoam. Ask them for it if you cant find it they will find it. Turn engine and ride around the block and back to get it good and warm. On the back side of your intake manifold (the big aluminum colored plenum thing) is a break booster line to the right there should be 3 rubber hoses there. Take off the small one that runs to the left into a 3 way plastic piece from the plastic piece and put that into the can of seafoam and SLOWLY extract 1/3 of the can into your intake manifold (their should be suction)! After you get 1/3 in there go and turn the engine off and let it sit for 5min. Ok turn the engine back on and be amazed at all that white smoke coming out of the tail pipe (dont worry this will not harm your engine if done correctly). Idle it for 3min and drive it around the block and back and that white smoke will eventually go away. What the smoke is from is carbon build up and it getting cleared out with seafoam. If your engine is running bad still then come on back to the forum for more info.