JDM H22 w/engine code please help!

i've got a 93 JDM h22 in my 91 accord and it hasn't been running very well lately. It likes to stall once its warmed up and the idle will drop real low...sometimes the rmps with go back up and other times it will just stall out on me. It also doesn't feel as smooth or as peppy as it used to...it seems like its either getting a little too much gas or not enough because it jerks when you take off slow. I was thinking it could be the fuel pump or the injectors but i just wanted a second opinion. VTEC also stopped kicking in the other day..sometimes it wont kick in and other times it works fine. I got engine code 12 and 21. 12 is EGR lift sensor(exhaust gas recirculation) and 21 is the VTEC solenoid. im sure 21 is causing the vtec prob. but what are the symptoms for the EGR lift sensor? i'd appreciate any info..thanx