my car has 255k its 92 vx hatch. for quite a while now its been stumbling for 2 or more seconds. its happens when cruising--i.e. if im going 65 and i let completly off the pedal and coast for a second then i step on the gas to resume my 65 mph speed, the car will stumble. feels like its misfiring. ive hooked up the dso to the tps and the map sensor and looked at the voltage and the waveforms both are normal voltage and healthy waveform. injector waveforms are perfect. now i want to check the wave form of the o2 but its a 5 wire sensor and im cant figur out which to probe. any help or if anybody has had this problem before it would be much apreciated.

 

with that many miles... i suggest a motor swap

to something stronger or maybe just a D16. Swaps are what EG's are made for