Spark plug Bosch or Champion

In my B3 Vr6, about 3yrs ago, I swapout the NgKs to Bosch Fusion 4-prones and my mileage went from 17 or so to 32mpgs. My car responded better and better mileage.

I've been using Bosch FR8LDC in my car for years with good results.

Now running the Bosch +2 Platinums and my MPG jumped from about 21 to 25! A lot of others will tell you not to mess w/ the platinums but they are doing well for me.

I got... bosch platinum plus plugs... and you could feel the difference right away with the new plugs. started faster, idled smoother

As for your plugs, bosch is deff the recommended brand, but just about any high quality plug designed for your engine will work fine. (im currently running platinum in mine, and their fine, but lots of people have reported idel issues with them.) The motor was designed around a copper plug, so thats what it should run on best. so bosch copper is deff the way to go.

newer Bosch plugs, cap, rotor (maybe 15k ago)

Changed spark plugs, wires, cap/rotor with Bosch bits (w7dtc not those crappy +4s)

Personally I've never had any luck with ngk's in any of my vr's always just run Bosch plugs and wires....

First step, get those Bosch Platinums to a trash can where they belong. Even when I was in Bosch Fuel Injection Training School back in the early 90's, the Bosch Instructors were telling us not to put them in anything unless we wanted to start chasing driveability issues.

I'm a technition with many years under my belt.... and had numerouse out of the box brand new BOSH plugs that upon installing them were dead, not just one but two in the same set, i would then take em out, check gap, and spark test the plug wires and coil, swop them to a diff cylender and bam.. still crap, im not trying to knock them and im not and NGP rep, im speaking from experience