My 96 is acting weird, seems to be in the morning only, or after first startup. I start it drive it out of the garage, backup to the flat bed trailer or just run it a few minutes and shut it off and then it wont start again, it turns over good but no fire. Open hood tap on fuel shutoff valve (with key on), press on the throtle and most of the time it will start, some times it takes two trips under the hood, so far it hasn't been towed or abandoned. Starts good the rest of the day. Whats going on?