running rough at low speed

[kwdvm87]

Hoping for basic advice, i know it can't be specifically diagnosed this way. My 22 Big Bend has started running rough, most noticeable at low speed, around 30mph. No check engine light.
List of possibilities? Bad gas? Transmission? Needing tune up? It has 91000 mostly highway miles. Have done oil changes on time, and i think last time they did the fuel system treatment.
Just hoping for ideas before i take it in.
Thanks

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[Brian_B]

Checked the plugs? Even if you don’t change them how they look can be a good clue, but 91k is about that time. Air filter good to check too. Do these things have a fuel filter, or is it part of the pump to make it totally difficult (I admit I haven’t looked - I think it’s integrated but not 100%)

A tune up on these engines is basically an oil change, new air filter, new spark plugs, and make sure the radiator and intercooler are clean

 

[Dover157]

I would definitely lean towards plugs. Also which engine? If the 2.3 being GDI only the intake valves may be gummed up with carbon.

 

[adam1991]

Clearly you cheapened out and used the wrong octane gas.

<d&r>

 

[kwdvm87]

Thanks for the replies. I was hoping a tune up might be the answer. It is the 2.3 engine. And as for cheap gas, possible. I only use premium from top tier stations. But husband and daughter have used it lately and there is no telling where they got gas.

 

[B22-2023]

Clearly you cheapened out and used the wrong octane gas.

That deserves a "I see what you did there!"

 

[Tricky Mike]

I'd definitely try new gas before getting too invested. I recently was chasing a miss at idle on my F250 only for it to go away on the next fill up.

 

[kwdvm87]

Thanks. Filled up at Costco tonight . Will be due oil change in a couple of weeks anyway. Hopefully the gas helps

 

[CitrusBronco]

As previously stated, your due new spark plugs at this mileage. I would change them now as they are at the end of service life and worn by now, you gain no benefit to wait until they fail first. Affordable and easy enough to change at home also.

 

[kwdvm87]

Thanks! That's the plan.

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