On 3rd head being replaced under warranty.

I would suspect the injector. I don't know if they flow test DI injectors like port injectors. The spark plug should tell a story if that one cylinder is running lean

 

Or….the original cause was a tight valve and the clearance wasn’t corrected.

 

the full Platinum package is what $1300~$1800 from our "known" source for them and can be bought before the orignal runs out
not insignificant, but a chip compared to the chunk out of pocket would hit
if I was in your position and wanted to keep the truck I'd get it

 

Most likely there was some nicks but didnt get to see the first repair before they had everything back together. I requested this time to take a look. Also there could have been valve debris but it’s all speculation.

 

Great point!
I’d shop the extended Toyota warranty for best price well before factory 3/36 runs out to CYA.

 

I think that's wise, could be a deeper internal issue that's going to keep going on.

I think worst case maybe but he should shove for that since it's twice now.

 

same cyl. twice now. thats would really concern me. I'd probably get rid of that thing after its fixed. maybe getting toyota involved will get it fixed correctly this time but I'd never feel comfortable about it.

 

My 99 4 cyl Taco got burned valves before 90k which eventually caused the exhaust manifold to develop a crack or perhaps visa versa and it really annoyed me and I've tried my twisted logic for years wondering why.

The independent tech in Arizona who did the wet and dry cylinder leakdown test said cyl 1 and 3 were 30psi and 60 psi. the other 2 were over 100. The tech who did the work said he had only seen that from cars that lived most of their lives in California insinuating it may have been the gas. Needless to say I traded that in.

One thing I know about that truck bought new was that my commute to work was short, 2 miles max for 2 years and I don't think I ever got that truck to temperature on my work commute. Or perhaps it was that oiled K&N that I started using 3 years in that ruined the engine.

Needless to say now I always get my current truck to temp with the idea that short commutes are bad for an engine and do a monthly Italian tuneup.

Just spit balling an idea - I am not a mechanic.

Disheartening to see these issues. So many variables. Spent hours reading about the potential causes over the various threads related to this.