1997 dodge ram 5.9 v8 4x4..truck had a fire under the hood..items replaced include wiring harness, dist. cap & wires, fuel rials, hoses, intake gaskets, coil, cam shaft sensor, crank shaft sensor, IAC valve motor, etc. It will crank, but once at an idle it will go dead just like the key has been turned off. When holding accelerator at 2000 RPM it will run rough, at 700 RPM it dies. Has been to mechanic and hooked to computer. No codes showing what is wrong. Mechanic got it running but can't fix idle problem.