I have been experiencing a strange problem for a while now. Under perfectly normal driving conditions, my engine surges. The best way I can think of to describe this is like an oversized AC pump is being turned on and sapping power. It almost feels like a cylinder isn't firing. I adjusted my valves and my timing to exactly what the factory manual suggests, and the problem got pretty bad, meaning that I lacked power pretty much all the time. I advanced the timing through a couple of settings, and eventually (as expected) it started to ping, so i'm back to the factory settings now. My lights were also surging, so I replaced my alternator because it has an integrated voltage regulator and it solved the light problem. I replaced my spark plugs at the same time, and a couple of them looked really fowled and messed up. Also, the engine has trouble idling steadily through an interval of about 2 min after startup until about 4 min after startup (hope that makes sense). By the way, it's an '88 4ZE1 which I rebuilt. OK! sorry for the excruciatingly long post, but I hope some of you have some insight as to why this engine is running so crappy. Thanks!