[USMC302]

I second Dark's suggestion about removing the smog pump, if the cats are gone, it has no purpose. The clicking you heard, was it more like a pinging? Could be timing. Do you use regular unleaded all the time or supreme? Maybe try running supreme through it and see how it acts. The tune up would be a good route as well, fuel filter, plugs, all factors that could be culprits for what your describing. Good luck.