Well, it's dead now..... apparently I didn't get all of the pieces out of there from the broken rocker arm when I replaced it, and one jammed under a cam lobe and stopped the cam. Sheared the alignment pin off the cam gear and threw the timing belt.... of course it did this 700 miles from home (but only 10 miles from my destination). I left the truck there, and am trying to decide what to do. I have a spare engine I could pull the head off of. Or, I could get one of those cheap new 4D56T heads off of ebay ($600 from maylasia). Do they just bolt right up to the 4D55T block? Is it possible that this is a bum head for some reason?.... it failed back around 1995 originally (I think it was a dropped valve, but it might have been a bad rocker arm then too -- that was before I owned it) and was rebuilt, then had a broken rocker arm foot in 2005, then again in 2012 -- all within about 35k miles. Rest of the engine has always been good it seems.

It got 27mpg on the trip... was running really good, except for some electrical problems (which didn't affect the engine).