Ok so here is my situation. My 1996 lexus ls 400 starts fine. Sometimes when I start the car it will drive fine but then out of nowhere it starts to hesitate and I loose power. I am getting codes p0172 and p0301. Have changed spark plugs and wires, Fuel filter, fuel injectors, misc vacuum hoses and the egr valve. And still having problems. 3 spark plugs keep getting black. Coil packs are good. Cats are good. O2 sensors good. The mechanic gave up on me today. Please help.