I've been have a strange problem with may car for some time now. I have to leave the key on for a bit to get it to start. Sometimes I have to hold the gas peddle to the floor and then it seems like a timing problem. I can here it backfiring under the passager floor board. It will start OK when it is cold but when it's warm like when I stop for gas and take off agian it's really hard to start. I've noticed that if while im filling up I just leave the key on it will start easier.

It's seems like it's not getting gas but the fuel pump pressure is fine and the filter is new. Could it be timing?

I've never had a time were it didn't start it just takes a little bit to get it going some times.