My 2004 touran struggles to start under hot temperatures and idles rough, however on a cold start it fires up nicely and runs how it should

My 2004 touran struggles to start under warm temperatures and idles rough, however on a cold start it fires up nicely and runs how it should the idle is also lumpy and I can also hear a faint thumping sound coming from the engine bay while sat in the drivers seat with the engine running any help or advice would be greatly appreciated so I know where to rectify the issues with my trusty touran