The slow throttle response could have been due to a carburetor fault paul, or the the rubber timing belt that drives the overhead camshaft might have jumped a tooth or two. You said you have checked the timing: did you check the camshaft timing, or the ignition timing? I know you have had a past thread where it was the timing belt, so you probably meant that, but please confirm.
If the camshaft timing is correct, we will need to discuss in detail what you did when you serviced the carburetor. There are other possibilities as well, including loss of compression, and perhaps a sticking centrifugal governor mechanism, but let's begin with the most likely problems.
