Its starting to sound like you need to complete a good service - good oil & filter plus decent plugs and possibly an air filter then start trouble shooting - check the codes, check all your earth contact points are corrosion free, check your tubing for splits / leaks, check for a spark - even though thought that could be breaking down under load
I would echo Mr B and advise caution whilst you are investigating because if you are driving around still boosting fine but having fuel dropping off you are going to run lean and that is like turning your blow torch flame from yellow flickering flame to bright blue and it will burn through your pistons in no time