Basically my 85,000 mile 1997 8V Gti bogged and hesitated when accelerating through 2,000 to 2,200 rpm when warmed up and was sluggish past 4,500rpm in 3rd, 4th and 5th. It also kangerood when slowing down through 1,500 rpm in any gear. I'd already fitted a new rotor arm, dissy cap, plug leads, plugs, ECU and fuel pump relays, vacuum hoses and a known good replacement throttle body in an attempt to sort it. VAGCOM said it was potentiometer "control" and the plug tips looked white indicating a lean mixture.
Removing the leads to the Mass Airflow Sensor resulted in a loss of idle initially but the engine instantly regained all it's previous power and flexibility. I removed the MAF and very carefully cleaned off the black residue with Electrical Contact Cleaner spray from Maplins (£3.50) After letting it dry naturally and refitting it, I had my old Gti back and it's been fine for the last week or so. According to the trip computer the mpg is much the same. VAGCOM shows no errors.
Sorted
P.S. I cleaned out the throttle body last year when idling became an issue. The car has never had an after market air filter fitted
