I'm working on this 99 RX300, and I've got a handful of ideas for what COULD be wrong, but nothing conclusive. In the morning when it's cold, it's a little difficult to get it started, have to give it some gas for about 20 seconds to get it running, or it will just die. Once it gets going, it idles up and down like pulsing fairly quickly. If I give it a steady amount of gas to get the RPMs up about 1000 and try to hold it there, it still goes up and down from that point. While it's idling, there's a smell of fuel all over the engine compartment as if it's running really rich, and if I open up the air cleaner box, I can hear the air wooshing in like mad. I disconnected a couple vac lines to introduce a vac leak and it made no difference, and I could feel no vac on the hoses when I put my finger on the end, which makes me think there might be a vac leak. It's popping the CEL with error codes for a few sensors, the only one I remember for sure was the O2, I need to get the codes pulled again and write them down. I noticed putting my hand in front of the engine above the exhaust manifold, between the engine and radiator, I could feel warm air gently blowing out which seemed out of place with the fans off, and made me think there's an exhaust leak. The strange thing is, taking it out of park with my foot on the brake and everything evens out and it idles and runs fine. I'm stumped. Anyone have any ideas?
