What is the solution to my problem detailed below

I removed the insides of my catalytic converter, after I put it all back together the engine light would not go out, after a few days when my van got up to temperature it started to cough and sputter, lacking power when under load. I ignored it for three or four days, also I kept smelling exhaust, which caused me to re-check that there were no leaks from the exhaust system, a few days later, when accelerating it began to clatter inside the engine. Major noise. Someone suggested that I had either a lifter going or my catalytic converter was clogged, causing chaos. This caused me to remove the pipe with the converter on it again to make sure that it wasn't clogged. I could see the light from one end to another, then I stuck a hose through from one end to another, then I blasted it with water from a garden hose, it is totally clear, nothing inside but empty pipe. I put on ear muffs and ran the van for 10 minutes without the exhaust on it. It was too loud, I couldn't tell if the clatter was still there or not. Two days later, after I was sure all the water was gone from the pipe, I re-installed the pipe and converter. The van ran fine for twenty minutes or so, on a hi-way run, my engine light never went out though, then after it got hot my coughing and sputtering started up again. Like pressure is building up, and messing with the valves. Or?