Drum roll please...
the R53 is back and mechanically sound! Or at least operational.
The engine is in time, although it took the shop two attempts. On the first try it was out of time after one revolution of hand cranking. No idea why. They did it again and cranked by hand a few dozen times and it remained in time.
the misfire seems to be gone. Now that the engine is properly timed, the power band is back to normal. No error codes, no engine light, no misfire to hear or feel, smooth idle... we think this six-month-plus ordeal is finally over.
Now, we do have oil leaks to address but not as serious as I feared. Mechanic confirmed the oil pan is not leaking and the rear main seal is not leaking - great news. It’s all coming from the oil filter housing and the oil cooler connected to it. I had the filter housing out to put in a new gasket so that may be the whole problem. The oil is getting out from there and wicking it’s way across the back of the block and then up into the gaps at all the seals, so it looked much worse to me.
Also I will need to deal with the power steering leaks as mentioned. At least it’s good to know that is common. Last detail is the front axles aren’t sealing correctly and they’re leaking. Those were installed at a different shop just before I started this project so I need to talk to them and see about getting them to check their work.
I think I can finally close this insane thread. Never in a million years did I expect to be adding to this story in June... it was winter here when I started this! But I also didn’t expect all the helpfulness and incredible generosity of time, ideas, thoughtfulness and talents of the members of this forum that followed along and offered advice and help along the way. Everything I’ve done has been trial by fire, learning as I go, and you all served as my primary resource throughout the process. So, thank you!
I’ll start a new thread for whatever I get into next. For the time being we’re just going to enjoy the car and a little free time while it leaks a bit, and I’ll plan my attack for those fixes soon.
Meanwhile I haven’t even driven it yet - my son picked it up with me, he drove it home and went back out for the night. He’s been without his car for a month, the final month of his senior year of high school, so he’s extremely happy to have it back. Hopefully I can steal some seat time in it this weekend.
Winner x 3