Dizzy2217

My 98 mustang is reading a code for multiple misfires. I ordered the screamin demon coil packs an new spark plugs. It's have a rough idle an at cruising speeds it chokes a bit. Should this fix the problem

Urambo Tauro

Maybe.

Have you looked at or tested the parts you're planning to replace?

Z28KLR

Please post the actual code(s) you're getting.

Dizzy2217

P0300

Dizzy2217

I didn't know how to test the coil. Western auto said the coils due to being factory coils an I have 130k miles need replaced.

Urambo Tauro

Not a bad idea at that age, but hardly definitive. I've seen stock coil packs still going strong well past the 200k mark. You can run a resistance check with a multimeter. The spec for primary resistance is 0.3 to 1.0 ohms, secondary resistance should be 6.5 to 11.5 k-ohms.

A new set of plugs isn't terribly expensive, and if they're the original ones, then yeah it's time to replace them anyway. But I see that you didn't mention wire replacement. Did you already ohm them out?

Keep in mind that there are other possible causes for your symptoms, but at the car's current mileage, a tune-up (if it hasn't had one yet) is a good place to start.

Z28KLR

Here's some more info on P0300.....
www.obd-codes.com/p0300

I would go with the above suggestions for now - new plugs (try that first), new coils (since you already ordered them, but normally I'd say to wait and see if new plugs cured the issue), new fuel filter, clean MAF (there is a specialized product for this, do not use anything else such as carb spray or brake parts cleaner or you will fry the MAF). And I almost forgot - your car has actual spark plug wires, so you may also look into replacing those as well. Unless you see one or more with obvious damage though, I would run through the less expensive items like plugs and fuel filter first.

For plugs, if unsure what to get, I use and recommend Autolite 764's (regular copper plug). If you want stock replacement platinum plugs (think Autolite AP103 or 104 is a stock replacement) then go for it, just don't spend a bunch of money on plugs coated with Unobtanium, have multiple electrodes or that promise more hp and 10% increase in fuel economy. It's all advertising BS.

Dizzy2217

Ok thanks guys the coil should come today. The plug wires are relatively new 8mm wires. The have no external breaks an fuel filter sounds like a good idea along with plugs any ideas on the no plugs.