220K miles intermittent rough ice start.

So my 2012 Prius started to do the rattle upon ice start and got a code for a misfire in cylinder 1. I changed the plugs (cylinder 1 plug was fouled up the other 3 were good) changed the ignition coils. Car runs much better and typically on a normal day ice starts great and runs great until the car gets warm and it goes into ev mode then I accelerate at the ice kicks in and starts rattling untill it equalizes. I have also noticed it's drinking up coolant like crazy I noticed it was low filled it up to full and it's down past low after like 80 miles of driving. I also did a combustion gas test and it came back negative and a compression test just getting it to crank over without the fuel injectors connected. I will attach the compression test results. I checked the oil via the dipstick and didn't see a milkshake but maybe I need to drain it to see if the coolant is getting in it? I am 99% sure it's a head gasket leak but would like to know if there is anything anyone can recommend to check that could cause coolant to disappear without any visual leak and the engine to run rough either when it's warm or when the weather is hot and coolant becomes pressurized. The fuel injectors intake manifold and EGR were not cleaned yet and I am unsure of when they were last cleaned. I plan to clean everything if I am to replace the head gasket but I don't see how they would affect the coolant disappearance.

 

The HV battery was replaced I believe at 160-180k as far as I was told when purchasing at 197k. The car was regularly serviced at a service but unfortunately they wouldn't help me get any service history since their records were done by plate or so they said. Since I got new plates it was kind of a dud lead. I would love to keep the car as long as possible this is my first car and honestly apart from this it ran fantastic I change the oil regularly and have done my own brakes and plan to do any work myself unless it's something out of my ability or requires special tooling that's not worth investing in. There is some minor rust but the previous owner had it kept in a garage and so rockers and everything is mostly rust free. Since it seems like this is most definitely a head gasket I plan to change it myself have the the cover machined if I can. I would get the intake manifold, fuel injectors and egr cleaned out while everything is off. I don't have an air compressor yet so would it be worth taking it to a shop to get a leak down test before doing the head gasket? Or what order should I do things in?

 

Actually I believe the HV battery wasn't replaced but reconditioned now that I remember. But I have looked into battery repair or replacement and don't see it as a major issue unless it dies on me unexpectedly.