I wouldn't be concerned Chris, if there was problem,you would have had it within the first 20k when you replaced the plugs. Most problems occur from the wrong style/design is replacing the original OE plug. Plug depth and heat range need to match up is the key. I personally run NGK's in everything I have. The River Pro, any race car engines I build, the go-karts,even the Farmall H in the shed. I have stayed away from Autolight and Champion plugs, they seem to be just good enough to plug the hole and have had nothing but issues with them.

Yeah Brian, I figured if something was going to go wrong, it would have.

I put these same Bosch plugs into my Ford Ranger many years ago and figured I'd put them in the Sierra as well. Both trucks... no issues at all with nearly 140,000 miles between the 2 trucks combined on those plugs.

With my snowmobile and boat motor, its NGK all the way.

I have not had too many issues with the Bosch +2. The real problem is the Bosch +4. Since The guys at the parts counters think the +4 are the greatest thing since the invention of the locking pliers and they always seem to be on sale (they have to get rid of them somehow) most people end up leaving with a set of them. The problem is there is no adjustable gap and they seem to require higher output ignition systems (coil over or other DIS systems). Typically the vehicles that suffer the most when these are installed are the older distributor type ignition systems and typically the problems show up in the late fall or winter.

I have removed more brand new +4's and replaced with O.E. plugs to solve many no start complaints over the years.

So to answer your question Chris, Your fine.

Although you are almost do for some new ones soon!

I work at a parts store and I won't sell people bosch plugs unless they really want them. The reason is that I have had enough people come in with problems. I think in some german cars they work fine, but I have just had too many people come in and say they just put them in their car and it ran worse than with the old plugs.
Stick with the delco iridium or get an ngk iridium. I have never had a complaint when someone goes with either one of those.

I am sticking with Ac Delco 41-985 at $6 ea and found a deal on wires on Amazon.com with free shipping and a rebate to boot. So My tune up will cost me $80 and I do the work. My dad has the same truck and paid $265 for a shop to the same thing and they hit him up for $12 a plug.

The +4 was a great plug. It has made me some money in the past.

Thats the name of the game*&%&%( sorry , stick with the O.E.M.'s folks.

I guess when you put it that way Shack, everybody should immediately replace there current plugs with Bosh Platinum +4's! lol

Bosch plugs work the best in the German cars. Don't get me started on them. I did my first T-Belt on a 1.8 turbo Passat the other day along with a turbo. $4,000 (yes thats 4 grand) later the customer was back on the road. By the way if the T-belt brakes on one of these (and they do right about 90k) it will run you about $5,000 to get it running again!

Reminds me of the Mercury Mercur.

I worked at a dealer where it was "our" specialty. What a bomb of a car that was. I think that was Fords try with German thoughts .