Ford Probe 2.0 liter engine issue

Hello all, I have been working on a 95 probe engine. The timing belt went smashing the valves. I replaced the head assembly and now have two new issues. First, one or more of the hydraulic lifters are tapping loudly. None appear to be collapsed, they all seem fine. So how do i locate the defective lifter(s). Second, I gave the car back to my friend and it ran great with noisy lifter and all for 2 days. Now it has no power and stalls. I tried to drive it back to my house, didn’t make it. My buddy followed me in his truck and he told me he smelled a very strong sulfur smell. I tore the engine down again today fearing the timing belt jumped a tooth, it did not. Is the cat failing or am I missing something else? This is a dohc 2.0 liter engine

The strong ‘sulfur smell’ indicates that the catalytic converter is cleaning up large amounts of unburned hydrocarbons. The fact that it has air to do the process and the lack of power indicates that burnable mixture is going to the exhaust. So look for the reason that is causing cylinder(s) to misfire or mixture to leak out of the cylinder before the spark. You may have mechanical problems that have not been corrected.

Let us know what the progress is on this.