My sisters Civic died on my drive way a while ago and I happened to have a d16y8 her car had a d16z6 my first thought was that maybe the timing was off enough to bend a valve based off of alot of clicking and clacking coming from the motor when it did run (after replacing the timing belt) long story short I pulled the head and found a bolt in cylinder one about 4inchs long and a quarter of an inch in diameter so I decided you can't break what is already broken that Bing the 2 engines so I pulled both appart and began to build one engine from the wreckage it was interesting to say the least the only thing that is still a Y8 on there are the block, the Pistons, valves, head and vvti solenoid

Somehow it works starts up it will hesitate then runs and idles nicely around 900-1000 rpm for about 1 minute then it slowly dies until it stalls I can restart it it will behave the same way if I hold rpms at say 3k it will drop rpms quickly until it dies in the same fashion also not related to engine temp the engine behaved the same at a could start as it did when up to temp

I'm asking what to look for next in hopes that it is something simple that I missed other then the fact that that engine was bootlegged together on a budget with a first time engine builder trying to make it work