Lexus215

My car shakes while not moving.. Its not the motor mounts because my car pudders really bad. My whole car shakes it feels like my car needs a tune up, but I've already done it. When I rev the car it just pudders really bad. Also my check engine light is on, and the lights in my dash are like flickering.. I also smell unusual fumes coming from the exhaust pipe. What happen was I left out of town for a few days and I let my cousin use my car for the few days... And now that im back my car isn't running the same. I asked him what did he do, he said all he did was drive the car. Which I don't believe this was a perfect running car. it has only 84k and it s 91 LS 400. I know one thing for sure I will NEVER trust him again. Thanks for all the replys!!

I have a 91 Lexus LS 400 and my car shakes really bad.. What I did so far was give it a full tune up plugs,wires, etc... The car still shakes BAD what else could it be? Could it be any relays, ECU, etc?? What should I check for? Help Please