Hi

Vehicle after some distance driving at steady speed @around 60 mph goes flat & wont increase speed when you accelerate, if you release throttle slightly & re apply vehicle will accelerate normally for some time until same fault re occurs. Nissan diagnosed EGR valve over 12 months ago & fitted new valve, fault has returned now & reoccurs every 10 -15 miles .Carmen scan shows egr volum cont fault and occasionally air mas volume cont fault, system will reset & run ok for another 20 -30 miles & reoccur (stepper motor type egr valve

Any ideas please

Derek