1997 honda civic DX hatchback. automatic transmission. 164k miles. all stock ........out of no where my civic has decided it wants to have multiple misfires on almost every single hot startup. assuming its multiple because the check engine light that came on was multiple misfires so I am assuming it is that every time. This is the only time it ever happens and quicky fixes itself after 2 seconds of starting. when it first starts the rpms are low and the engine starts shaking just like it wants to stall. my car runs amazing all other times. this is strictly upon initial hot startup. have replaced with high quality ignition parts and new spark plugs correctly gapped. new pcv valve, new fuel filter and new oxygen sensor. throttle body cleaned etc. so all parts that I can think of that are in relation to starting are new. I don't know why its only at startup and no other time. all 4 spark plugs look like they should, cars running pretty nice. my car has never stalled from the problem and starts every time but its an obvious problem now. the only thing I can say is I beleave it started happening after I changed the pcv valve and a bosch oxygen sensor. also after the only time in the last month I decided to go WOT from a stop and got a loud slamming wheel hop bang. I doubt that's related. I have also checked all connector plugs and unplugged and reconnected all plugs in hopes it was a bad connection somewhere. trying to be as specific as possible

 

Guys I was mistaken I thought I remembered it on every start up but it seems like it happens more when it's warm because I did a coldstart this morning and it idled fine right from the start. hoping maybe it would have an easier answer if it was just warm start ups. There is definitely some minor valve tap that can only be heard when cold. Also update today the car almost didn't even start installed out a couple times before it got idling again. Need help guys