Small problem...please help
 

Ok so here is whats going on. I have a small miss fire, not a problem, The big issue is at around 45-55 its bucking. But I can still force a down shift out of it.

4.0l with an AW4.

Any help would be great thanks.

Does it do it when in neutral and you rev it to a certain rpm or just while driving. Also how many miles and have you done any maintenance.

No it only dose it when driving. I need to change the oil. I put plugs in E3 about 2 or 3 months ago.

Tune up sounds like it is in order.
Plugs,wires,air and fuel filter,distributor cap and rotor etc.
For me the cap and rotor is a big one because many people over look this during a tune up.I even did once on my s-15 jimmy,the thing was missing like crazy and I assumed the worst after doing the above mentioned items.I finally took a look at the cap and rotor and the contacts were burnt all to heck.Installed new and the thing ran like new! :)

When doing the plugs keep them in order of which cylinder they came out of and take a good look at them this way if something else is actually wrong you can use the condition of the plugs to help determine the problem and which cylinder is the culprit.

x2 on basic maint first. Then you have a fresh base to start with.

Sorry you replied while I was typing :).
I would check the plugs any ways as I said they can give you important info.
Fuel pressure? Change your fuel filter.

If you have a fuel delivery problem and you are running lean it'll show on the plugs. They'll appear white/gray.

A motor uses more fuel at the same RPM when its under load. Free revving the motor doesn't reproduce the same senario that is created when you are actually moving the truck via the motor.

Loose, crappy explination....

3000rpm at free rev, no movement may use 1/2 gallon of fuel over an hour.

3000rpm under load while moving the truck may use a whole gallon over an hour.

Not exact numbers, but you get my point hopefully.

The fuel pump may be able to supply the fuel for free revs, but under load my not be able to keep up.

After reading your reply this may not be your issue. If it is missing then it will usually do it at idle as well if it was the dist cap or something of that nature.I would check the cap and rotor though just to rule it out if it has not been changed in a while.

You may be dealing with a fuel or TPS issue

It'd be nice to pull a plug, though, as it'd show a lean condition if its happening.

I agree. Sorry my previous post was in reference to my previous post lol I know I gotta make things complicated.