Facebook chat is just buggy as hell. It does that to everyone.. What I do is just refresh the webpage all the time.. Like once a minute.. And everytime you send something and it just says "Sending" Refresh it and it'll send, but sometimes it'll send twice for some stupid reason.. Its annoying as...
Sounds like Fuel Filter may be clogged.. The gunk settles when the car is sitting, then gets pushed into the filter when you drive and gas can't get through..