At 170K, I would very strongly suggest you find a way to do the valve guides. I know what being ''short of cash', means but you owe it to yourself. when done, you can forget about the top end for an other 150K+.
Do not clean the tip of the injectors with anything abrasive. You'll ruin them. Only liquids and rags. If you can find some toluene, it would be the best stuff to clean it. I would also check the head with a straight edge to make sure it is not wrapped.