Hmmm, with that mileage I'd be interested in the condition of the timing belt, but I'm not sure if SPI's are belts or chains since I've never owned one.
You should test the coil pack, and if you have lifetime warranty wires, replace those also. The fuel filter is supposed to be changed every 25-30k miles. If you haven't replaced it, then you should definitely do so. As far as the sensors, wait, I always suggest catching up with regular maintenance, and then testing to determine what is causing the problem. I'd also pull the spark plug wires and see what kinds of deposits are built up on the plugs. I'd then use a knife to clean the plugs, and check the gap before re-installing.
As a guess, when was the last time you changed plugs? Sometimes spark plugs loosen over time. This generally causes a problem when the engine is cold, and at low rpm. If that is your problem, great, but you should definitely catch up on regular maintenance.