Dont feel bad I am currently working on a 96 z24 2.4 quad4 with the same issue, The car has 35,000 miles, was only drove 5 mils a day and a older layed owns it. so it has never seen abuse, rough housing of any sort. So far I have changed coil pack, fule pump, crank & cam sen, pcm, nothing has changed. I have a cirt gm guy look at it, he told me it was security locked, tryed to reset it. nothing, changed key switch, ipc (gauge cluster) and still the issue remains. I am running out of things to change/ try myself. I am unsure if the cata is pluged, that is my next step in the morn along with testing injector wireing, tps, and changing injectors all together. Be rest assured if i find the problem on that car i will let you know the next place to check.