I think your chasing the wrong thing to fix, take your time to figure out exactly what is causing it to not run good when warmed up
I'm not sure where you live or where the car was driven in it life but you could have a grounding problem with the car or ignition system, works good cold and then heats up and then doesn't work good
Good luck, keep us in the loop, we, you and all of us on here, will be glad to help you find, identify and fix the problems