I understand there is not much adjustable on my 98 Ranger (2.5L) as far as idle speed and mixture. It runs rough when started cold. Is this a sign to replace spark plugs?
Any other suggestions? Thanks.

 

Could be, but are you up to date on All due specified past & present scheduled maintenance replacement items, like plugs, wires, filters, PCV valve, O2 sensors???? If you have a lit CEL, most autoparts stores will scan the computer at no cost for trouble code trouble shooting clues, then post all Numbers found.

 

wires and plugs at minimum. I dont know the brand or age of yours, but I have had real problems with finding plug wires that last any real length of time. I first tried autozone lifetime wires and then bosch lifetime wires (free replacement) and still replace them at least once a year.

I have not shelled out $50 for ford brand. But being cheap, at this time I just replace em for free over and over.

But yeah, rough at idle to completely missing and throwing a CEL are what I get for symptoms.