Hi. My ride is a 1997 3.0 MV6. The check engine light turns on from time to time especially when in traffic. Scanned it using Tech II (I have my own at home) and it says EGR.  After clearing it the light goes off. My question is : If I blank the EGR, what effects will it have on emission and over-all performance?
TIA

NOx will rise at cruise and cylinder temperatures should rise a little (though not by an important amount), performance slightly up. NOx isn't measured on the MOT, though, so you're fine there.

IIRC you must keep the solenoid connected otherwise the ECU will throw a fault, but can blank the exhaust connection side safely.