'96 4.0L hesitation

[Lukekool]

I am getting ready to troubleshoot it tonite and just wandering if anyone might have any ideas on what to check or do? It idles and runs up up through 1st and 2nd through the transmission just fine. but when i get up to highway speed it starts hesitating, missing and bucking a lil. but when i give it gas to get higher RPMs say to pass it's sounds and feels fine also. another thing when i have cruise control on it has a rought time maining speed up hills no matter how big or small. from what i read so far could it be MAS that needs to be cleaned?

 

[Mirge]

I am getting ready to troubleshoot it tonite and just wandering if anyone might have any ideas on what to check or do? It idles and runs up up through 1st and 2nd through the transmission just fine. but when i get up to highway speed it starts hesitating, missing and bucking a lil. but when i give it gas to get higher RPMs say to pass it's sounds and feels fine also. another thing when i have cruise control on it has a rought time maining speed up hills no matter how big or small. from what i read so far could it be MAS that needs to be cleaned?

I'd check plugs & wires...

 

[Lukekool]

I didn't think about looking there since it's ok at idle all the way up to highway speed. Ill check those out

 

[Mirge]

If you have a multimeter the wires are easy to test... worthwhile, and sometimes overlooked.

I've had hesitation/stumbling issues at various speeds on a 98 Mustang GT, 96 F-150 V8, 98 Mustang V6, and 98 Explorer EB... every time, new plugs & wires solved it 100%... so that's why I recommend checking the resistance of the wires at the very least. Cheap fix if it turns out to be the culprit.

 

[Lukekool]

What should the resistance be?

 

[Mirge]

Can't recall off hand... http://mr2.com/TEXT/DavidKucharczyk/ignition.html may be of some help.

When I checked resistance, I basically just checked to see if any single one of them had what I felt was abnormally high resistance. Some would have 40 ohms resistance, others maybe 60 ohms... then I remember on the 98 GT, I ran across one that was ridiculously off the charts high. General rule of thumb is if you run across one wire with high resistance, replace 'em all... at least, that's what I'd do .

Not sure which specific motor you have, but for my 98 Eddie Bauer, whole set of plug wires was around $45-$50 if I remember correctly? Wasn't bad at all.

Of course, it may not be the problem at all... but it's just *always* been the culprit in vehicles I've encountered the problem on. I'm sure others will chime in with other suggestions as well!

 

[dean1997sport]

I am getting ready to troubleshoot it tonite and just wandering if anyone might have any ideas on what to check or do? It idles and runs up up through 1st and 2nd through the transmission just fine. but when i get up to highway speed it starts hesitating, missing and bucking a lil. but when i give it gas to get higher RPMs say to pass it's sounds and feels fine also. another thing when i have cruise control on it has a rought time maining speed up hills no matter how big or small. from what i read so far could it be MAS that needs to be cleaned?

I know this post is REALLY old but did new plugs and wires solve your issue? I have the exact same problem..........