I have a 96 Neon with 140,000 miles on it.In the past year, the service
engine light has been on and off - (on for a few weeks, off for a week
or two, and back on again).The code says "cylinder one misfiring - lean
fuel/air mix." There are some hesitation here and there when stepping
on the gas.I have tried putting in new plugs/wires, changing the fuel
filter periodically,and having the fuel injectors cleaned.(Did improve
for a few months after the injectors and the rail had been
cleaned).Noticed the best thing is to put in a bottle of fuel injector
cleaner from time to time -lately I have had to put the cleaner in
every week. In the last month or so, idle is bad in the morning. The
engine stalls easily when I let go of the gas peddle. But idle would
improve and be back to normal after the car has been driven for a
while.Sometimes, idle sounds weak till I put in some fuel injector
cleaner. One mechanic found oil in cylinder one and claimed that oil
leak in the engine was the main probelm. He said it wasn't just the
gasket, and he would have to open up the engine block to seal off the
leak if he could. I suspect the problem is more to do with fuel
delivery. Is this mechanic right or should I go somehwere else for a
more thorough engine diagnostic? The body looks like  4/5 years old -
trying to hold on to it as long as I could.