'99 4.0 OHV rough idle
OK my 99 4.0 has been idling rough lately. When i first crank it up it acts like it wants to shut off and sometimes does. But if i turn the key off and crank it again it fires and idles fine until the rpm's drop back down to around 700 then the idle goes to around 500rpm and it tries to die again. When accellerating it acts a little sluggish but otherwise no problems there. The other problem is when cruising at say 60 mph i can feel like a little bump or misfire every now and then. But after the truck has warmed up it idles fine and doesnt try to die but you can tell something is wrong. Within the last 10-15k miles I have changed plugs, wires, all O2 sensors, fuel filter and the IAC valve. There are no mods to the motor other than a K&N drop in filter. Any ideas???
1999 Ext. Cab 4x4, 4.0, 3" PA Body Lift, 33" Nitto Mud Grapplers, 16" Ion 165's