S500L in trouble
 

Oh Dear, what is the problem. In my car as I accelerate the car seems to "hit the wall" at about 3000 rpm. It accelerates smoothly up to this point but stumbles after this, if i ease off the gas it shifts up and will do the same in the next gear, if i floor it it will get to a certain speed in first, then just slowly creep up the speed above 3000 rpm. I suspect a blocked cat as i rarely get to take it on long highway journeys, mainly just short distances around town, but i want to know if anyone else has had this problem, it is sad to see a V8 that gives up before it even gets into it's sweet spot. I also am concerned this could be a bad wiring harness as mine hasn't been replaced yet but fingers crossed it's only the cat and i can just buzz it out and weld in a straight through pipe (we have no emissions testing in NZ). If anyone else has a suggestion of what to check, let me know, how can i tell for sure if the cat is blocked without taking it out?

Oh and one other thing, if hit the gas suddenly it pauses for about 3/4 of a second before it takes off, I don't know if it is related to the problem or the car just has a slow throttle response - other owners with this engine please jump in your cars and stomp on the gas and respond

Found it
 

I did a search and another post suggested unhooking the exhaust to check the cat, not as easy as it sounds but seems to have tracked down the problem. One more question, if i cut out the cat and replace it with a straight pipe will this affect things like O2 sensors? Still have the slight pause with quick use of accelerator.