Nissan Maxima: 87 maxima won't start

Hi, I have a headache for 4 days now. Well is about my 87 nissan maxima
that died while my wife was dirving. I have checked the ecm codes and
replaced a maf and fuel pump. I have also replaced the tps and idle up
solenoids. The car ran like it was new and then two weeks ago while I was
gone on a trip it shut down on my wife while going home by my block. The
battery is brand new and I had the alternator check good. I really need
some help. By the way the only code now that pops on the ecm is 44.
Again engine cranks but does not want to fire. I also checked the firing
on the coil/spark plugs checked good.