Like 99% of all Gm vehichles with a 3.4 V6 my intake manifold went. I did it my self according to the book and managed to get the car back together however upon starting it it shook and rattled like the spark plugs were crossed and dies shortly after coming to life. Upon checking the wires to see if this were the case and coming up empty handed can any thing elemake a car run like that (i.e. a bad/damaged injector(s), a damaged wire to the coil pack ). If it was merely a damaged wire wouldn't the car still run?? There is a slight gas smell in the oil which is of course a sign of the firing sequence not being right but that being ruled out on my car (at least from the sparkplug end) has left me baffled. Any help would be appreciated.

Bought a 2005 RX330 from a local non-Lexus dealer couple months ago. It was auctioned because the previous owner failed to pay the bill. Recently during cold start, the idle RPM is between 1.5 - 2 and the engine roars quite loud. In addition, there's a slight smell of burn (not raw) gasoline coming out of the tail pipe. Currently it has 21k miles. What could be the problem? Is the problem covered under Lexus basic or powertrain warranty? Thanks.