engine pings and dings

and has less power when I use just regular gas , I think 85 octane, In order to drive smooth we have to use the good stuff in the star,, WOuld that be a cloged injector issue or is there something else that would cause it,
it doesn't make a sound when running on premium gas, but when the regular goes in its almost like a diesel.

thats my 99 star 3.8


thanks jeff

It will run much better after you do the isolator bolt fix because you will get an opportunity to clean out the egr ports. That will significantly, if not entirely, eliminate your pinging.

Make sure you clean those ports!

It is also a good time to do the plugs while you have it apart. With the cowl and upper manifold removed, you can replace the rear side plugs from the top.