98 Explorer idles rough/hesitates

[ThaaaCrusher]

Hello,

Year: 1998
Model: Explorer XLT
Engine: V6 SOHC
Transmission: Automatic

I've been reading throughout the web, including this forum, of what the possible causes are of a seemingly common problem in Explorers: the rough idle and hesitation at 35-45 mph. I have not really seen a complete thread solution for someone who has exactly my problem, so I'd like to describe it and see if there is some expert opinion that may be able to give me a clue.

Symptoms: As stated, idles rough no matter whether cold or hot (does not stall, though). When going 35-45 mph in overdrive especially, the X bucks and jerks badly. Outside the 35-45 mph range, it seems fine although there is a fairly substantial motor rumbling sound on acceleration after a tune-up was performed. No CEL light currently (when I did have it, the code was for Evap something or other).

What has been done:
Plugs, wires, fuel filter, Mass Airflow Sensor, EGR valve replaced
Smoke-test for vacuum leaks (small leaks fixed)
Injector cleaner added, TPS and IAC checked

I did unplug the MAS and the rough idle stopped. I would just disconnect it but the shifting is quite hard so I'd just like to figure out what is going on. Plus, I hate not fixing a problem.

I've heard numerous talk about the upper and lower intake gaskets needing to be replaced, but that would only make sense if the X ran badly when cold and changed its behavior (i.e. the tolerances of the motor got tighter to make up for the inappropriate thickness of the seals). That is not the case in mine (it runs badly all the time).

Any help would be appreciated.

Thanks.

 

[EnergeticDEPUY]

By any chance did u change the fuel pump or fuel filler neck. i was having a similar problem. There was contaminants in my tank due to a rotted fuel filler neck when i purchased it. now i have a code that says i running too rich or too lean bank 1 sensor 1 or 2

 

[ThaaaCrusher]

I didn't change it, but the fuel pressure was checked and seemed to be ok,

 

[dgafking760]

clean your throttle body also replace your tps mine got wet and cause rough idle and even stalling once i replaced it and clean the throttle body the problem went away

 

[ThaaaCrusher]

I can try it I suppose. Did you also experience the hesitation/bucking/jerking at low rpms when traveling around 35-45 mph? Also, we you getting a check engine light? I am not.

 

[albi1cnobi1]

If the problem was there before the plugs and wires, then you may have a bad coil pack. If not then possibly a bad plug or wire.