Originally Posted by Frango100
Did you check for any vacuum leak at the intake? Maybe a disconnected hose or dried out hose, which leaks? [/FONT]
Spray your vacuum lines with carburetor cleaner or WD40 with the engine running. If the engine speeds up while you are spraying, you have found a vacuum leak. It's best to use a nozzle extension so you narrow your spray pattern and you won't have quite the mess to clean up afterwards.
Another tip just struck me. There is nothing in the world better to clean and shine under hood plastic and rubber parts than GOJO. (Not the kind with pumice, use the soft stuff) Your plug wires will look brand new. GOJO and a rag are all you need.
Once you get your wires clean, run a screwdriver along each of your plug wires with the engine running and if you see spark jump to the screwdriver you have a bad plug wire. You can also check them with an ohm meter if you have access to one. YouTube will have videos.
I'm not as familiar with these new cars as I am the ones with carburetors and the word Magnum in the engine name ( and 340 or 440 in there somewhere) so pardon my ignorance. If your engine has a distributor cap and rotor button check those too. With over 300000 km on it I would be sorely tempted to do a complete tune up and go from there. Plugs, wires, distributor cap, rotor button, and fuel filter. Since you haven't had it long and you're not familiar with its maintenance history it will at least give you a starting point for future maintenance.