What are you guys using to dissolve the carbon in the intake manifold EGR ports? I used to use methylene chloride in the old days but the stuff is NLA.

 

Which engine are you referring to?
90-93 USDM 2.2 you really need to pull the plugs out of the intake runners and clean out the ports.
94-97 USDM 2.2 the EGR manifold it readily removable and easily cleaned with a flat head screw driver.
95-97 USDM 2.7 not sure, heard of removing some kind of plate and the egr valve.
98-02 USDM 2.3 EGR port can be cleaned by simply removing the upper plenum and cleaning out the port in upper plenum and the feed port in the lower intake to EGR valve.
98-02 USDM 3.0 EGR port can be cleaned by removing upper intake from lower and cleaning out the port in upper intake and lower intake.

EGR only functions during part throttle cruise, trying to get any kind of liquid or spray to clean it out is not going to be easy or fast, mechanically cleaning it is the best way.
Probably need to adjust valves too, so for the V6 this would also be the ideal time.