Working on my friend's 89 Sentra again. The other day it just died at the stop sign. Took the car to the mechanic and he said it needs to have the EGR Valve cleaned and the intake needs to be cleaned. The mechanic wants to charge him around 250. We were hoping to do the work ourselves. Has anyone had to do this, or does anyone have any ideas on what exactly this entails? Thanks for the help.