How do you or can you remove the carbon build up on a 1995 gmc jimmy I removed the erg valve and it was full of carbon how can you do more from other areas that has built up?

Technically, what you have is sludge buildup. Most oils deposit sludge on engine surfaces. Sludge is a waxy substance that precipitates out of heated oil. Unfortunately, there is little that can be done to completely clean out sludge from the inside of an engine except for a complete engine rebuild. The good news is, the sludge won't cause too much trouble all by itself unless a large mass is dislodged and plugs up the oil pickup screen in the bottom of the oil pan. I run fully synthetic oil in my vehicle because synthetic oil has far less sludge production. Unfortunately, you should not change to synthetic oil if your vehicle has more than 50,000 miles on it. You can use some engine cleaner additives to the oil that will partially disolve some of the sludge, but if you decide to do that make certain that you change the oil at short intervals to get out everything that disolves.

All of the answer above has nothing to do with the question. Oil sludge is a bottom side of the engine problem. The person asking the question already informed us it is carbon buildup in the exhaust. I don't know of a easy way to correct this except to remove exhaust system from the headers back and clean with carb cleaner. Then use a fuel additive to clean the injectors and cylinders.

ANSWER#3

I had a 97 Jimmy with a similar 4.3 Vortec under the hood that you might have 8/10 chances for that year. If you just bought the vehicle and discovered this, you might have had a previous owner that drove the vehicle with low acceleration which caused the high amount of blowby in the PCV and the carbon deposits slowly and coolly being left along your exhaust system. One way is to get a fresh oil change (thicker is better in summer), and drive the vehicle hard. I'm not saying to break the law as that is not something one should do. I'm just saying you can accelerate in such a way that you can maximize some hot air pressure going through the system for a week or so. This usually does get rid of built up carbon in the air exhaust system.