OK, and you used the previously mentioned plugs, the Bosch F8DC4's? It can make a difference.
You could try using a mid-grade instead of the 92 as an experiment, I have seen a few around this vintage, mid-1990's 104 engines, that did start better on an 89 octane, so that may be an easy fix. You've also got the other sensors I mentioned you can check. Lots of possiblities here, just mentioning a few I can remember.
I believe the tool to lock the fan hub is simply called the fan hub holding tool. There are a few different designs depending on the year, and I can't remember exactly which your would use, but i believe it's just a hooked rod similar to the 103 engines. Other possibilities are a handle with a "C" shape on the end with 3 drilled holes that fit onto 3 of the 4 bolt heads on the back of the pulley, or a tuning fork looking thing that slips over 2 bent sheetmetal ears on the back of the hub.
Since I work at a dealership, we get the stuff from MB. This takes time. if you need them right away, maybe someone in an independent shop can direct you to a fast cheaper supplier,or just try your web browser.