Rich, what is a GM TSB. My GTP has only 58,000 miles on it. I do not have any warranties on the car. If it is the catalytic converter being clogged, would this cause the car to seem like it doesn't have enough power to start the car(the only thing I can say to describe what happens). I have noticed several times that when I first start the car, its like there isn't enough power to make it run right. Does that make sense? It really runs rough, like it isn't firing on all the cylinders. It really scares me every time I start it. That is why I am wondering if it is the lifters and not something else. Just trying to pinpoint the problem. Even my mechanic told me it is so odd for a car with so few miles on it to be having several lifters go bad. God this car is driving me crazy. One time when I started the car and it was doing this with the not running right, my check engine light came on. I took it and had the code read and was told it was misfiring on cylinder 4. That is why I bought new spark plugs. The man told me to start there on the missing. Then proceeded to list a million other things I could do. Yeah right, like I have thousands of dollars to throw away. NOT.