After aprox. 10 miles of driving my car, a 1999 Sebring conv.lxi, starts missing. At first it's slight then gets progessively worse, loses power, starts back-firing, stops running. If I let car sit for an hour it start right up and runs fine for another 10 miles. Car sat all winter while I was in Fl. Had complete tune-up, new distributor, new crankshaft sensor, but problem is the same. The check engine light was going on, and showing a misfire, but the mechanic that replaced the distributor said he "wiped" the computor, and the light no longer works. I had a dodge years ago with a similar problem and mechanic forced air back to the fuel tank and blew the screen offin the tank and it was fine after that. There is a screen on the fuel pump on the sebring. Could that be the problem?

 

The first thing that I would check is the gas cap. If it doesn't vent air into the system you may have problems getting fuel out. Also, your fuel injectors may be fouled, working well when cold and the fuel mix is rich, then falling off in performance as the mixture leans out. Yes, there may be a restriction in a fuel line as well. Your EGR could also be operating incorrectly. Or an O2 sensor may be telling the computer to cut back on the fuel erroneously.

But it is most likely a fuel system problem. Without codes it can be difficult to diagnose.