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Hey guys... Still fighting an issue that I have, for the last two months, been unable to diagnose. I thought I had it licked this last sunday. I had the plenum off again, pulled the damper and timing covers, checked the belt, new plenum gaskets, all new vacuum lines, tightened all hose connections. Started up, ran smooth as silk, Take a little drive, seems fine. Come back, do a boost leak test, find a couple, fix those, take it for another drive, seems fine. Come home, check the oil, and the coolant, run to town, washed the car, put gas in, come home, she's sitting in the driveway idling, and all the sudden, the idle starts fluctuating. WTF?? Since then, when the motor is cold, it will idle fine, but as it warms up, the idle gets lopey, missing sorta, like a big vacum leak, then as the motor gets to where the thermostat opens the first time (full operating temp)it gets to where it will cycle from about 800 rpm (very rough) to 1150 rpm (somewhat smoother) then eventually idle down to nothing and die. This is cyclical, kinda like the AC compressor kicking in and out, but the AC is off. It is not "hunting" in the typical sense of the word. So, I bought a new OEM cas thinking something must be off there. Put it in, start it up, Started to get warmed up, and dropped down to about 800 RPM and I set the timing, holding steady at 15 BTDC. then, the whole thing starts over again, 1150, down to 800, 1150, down to 650, 1150, down to 400, 1150, down to nothing, it dies. As I watched with the timing light as this was going on, right before the fluctuation in RPM starts, the timing starts to waver by a couple degrees, the climbs to like 35 degree BTDC, and when the RPMs drop, it drops to like 9 degrees BTDC. It seems like the ECU is trying hard to compensate for something I cannot put my finger on. I have no vacuum leaks, but I cannot adjust the idle via the FSM method of unplugging the IACV and turning the screw, it makes no difference at all. I tested that again last night via boost leak tester, and all of the FSM methods. If I squeeze the hose that connects the AAV to the balance tube, it immediately begins to die. Squeezing the PCV hoses has no effect. I am out of ideas guys, what else would cause this issue?
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