hello im looking for advice on troubleshooting my truck. a year ago it was running rough so i changed my plugs, wires, dist. cap and rotor, fuel filter and it fixed the problem then just a few months ago i replaced the fuel pump. now its running rough again the symptoms are idles just fine full throttle just fine but part throttle it stumbles or when cruising it stumbles. now once it warms say 15 min it runs just fine again. the only code i have is random misfire. i changed the cap again last week with no luck so added berrymans fuel system cleaner and it ran fine until the next tank of gas. i had the fuel system cleaned yesterday with no luck also. any ideas on what this could be? i hate throwing money at a problem without knowing someplace to start. thanks for any info.