GREETINGS AND SALUTATIONS;
FIRST I WOULD LIKE THANK EVERYONE WHO HAS HELPED WITH THIS PHENOMENON THUS FAR. YOUR SUGGESTIONS HAVE HELPED HOWEVER NOT FULLY RESOLVED THIS MYSTERY. HERE'S THE HISTORY ABOUT 4 MONTHS AGO AFTER TUNING UP MY TRUCK ( 1998 DODGE RAM SPORT 4X4 WITH 5.9L V-8) I WOULD GET A CEL WITH THE CODE BEING CYLINDER # 5 MISFIRE. AFTER RESETTING THE COMPUTER IT WOULD COME ON EVRY 2 WKS OR SO. NOW HERE'S WHAT I'VE DONE TO CORRECT THE PROBLEM PER SUGGESTIONS:
CHANGED ALL SPK PLUGS AUTOLITE IRIDIUM, SPK PLUG WIRES MOPAR BRAND (REROUTING THE #5 WIRE PER SOME INSTRUCTIONS A FORUM MEMBER SENT WHICH ORKED FOR A WHILE), CAP AND ROTOR, IAC VALVE, BOTH O2 SENSORS, UPPER AND LOWER INTAKE GASKETS [ WHICH NEEDED REPLACING DUE TO THE OIL RESIDUE SEEN THROUGH THE THROTTLE BODY WINGS WHEN OPENED AND THE LOWER GASKETS BEING IN BAD SHAPE], REPLACED VAVLE COVER GASKETS, FLUSHED COOLING SYSTEM, CHANGED THERMOSTAT 180 DGR, UPPER AND LOWER HOSES ALONG WITH BY PASS HOSE, CHANGED TRANSMISSION FLUID, FILTER, AND GASKET. AFTER ALL OF THIS ESPECIALLY THE UPPER AND LOWER GASKETS IT SOLVED THE PROBLEM HOWEVER LAST WEEK [ ABOUT 3 WKS SINCE GASKETS CHANGE] IT STARTED AGAIN.
WE'VE SWITCHED THE #1 AND # 5 FUEL INJECTORS THINKING THIS MIGHT BE IT BUT NO LUCK THE PROBLEM STAYS WITH # 5 CYLINDER.
NOW I'VE NOTICED THAT THE TRUCK STARTS TO IDLE ROUGH DURING WARMUP AFTER ABOUT 1 MINUTE INTO THE WARMUP LASTING 5-10 SECONDS THEN RECOVERING. THIS OCCURS WHETHER IT'S COLD OR WARM WEATHER.
CAN SOMEONE TELL ME WHERE ELSE TO LOOK FOR A SOLUTION? THANKS!

 

#5 injector is prone to clogging. Remove and inspect the inlet side of the injector as well as the fuel rail. When you have done that, replace ALL of the O-rings atop each injector. Be sure to lube them with a light grade of oil or even PBlaster before reinstalling the injector/fuel rail.

 

another thing to do is run a compression test. I've seen as little as 25 psi difference turn on a cel.

 

I forgot to mention that a sticking valve causes misfires as well.

 

ROGER THAT WILL DO. WE SWITCHED THE # 5 INJECTOR WITH THE # 1 TO SEE IF THE PROBLEM WOULD FOLLOW ( IE CEL CYLINDER #1 MISFIRE) HOWEVER IT'S ONLY THE # 5 BUT I WILL REMOVE, CLEAN, INSPECT, AND REINSTALL ALL INJECTORS, O-RINGS, AND RAIL. ALSO HOW DO I KNOW IF A VALVE IS STICKING? HOW DO I CORRECT THIS IF THIS IS THE PROBLEM? I NOTICE THE MISSING GETS VERY NOTICEABLE WHEN THE FUEL IS AROUND 1/4 OF TANK OR LOWER BUT ALMOST NON EXISTENT WHEN TOPPED OFF.

 

WHAT'S A GOOD COMPRESSION TO HAVE?

 

Sounds to me like you have a clogged fuel filter, clogged pressure regulator, or even a dirty fuel rail if it only happens at ¼ tank.

 

WHERE IS THE FUEL PRESSURE REGULATOR LOCATED? THE FUEL RAIL ISSUE I WILL ADDRESS TO DAY AND I KNOW HOW TO GET TO THE FUEL FILTER. ALSO WHAT IS THE PURPOSE OF THE M.A.P. SENSOR?

 

I'd be looking for somewhere between 120 & 160. More importantly I'd be looking to see how even they are. You want them all fairly close to the same number

 

ROGER THAT! I'M GOING TO BY BEST FRIEND'S SHOP AFTER WRK, THEY HAVE ALL THAT STUFF OVER THERE TO CHECK IT. I JUST WANT THIS NIGHTMARE OVER WITH, HELL I CHANGED JUST ABOUT EVERYTHING THERE IS EXCEPT THE MOTOR. I THOUGHT THERE WOULD BE SOMEONE ON HERE THAT HAS EITHER HAD THE SAME PROBLEM OR KNEW OF SOMEONE WITH IT.