I looked further at your pictures and I looked under hood of my '95 2.5 port FI.
If the '95 intake manifold is identical to yours, I see cyl 3 and 4 fed by same runner. There both a vacuum port and vacuum sensor on this runner. Leaks on either will cause 3 and 4 to go lean.
Looking at your pics, cyl 4 exh valve is black because the cyl isn't firing with the holed piston. Cyl 3 exh valve shows the whitest, hottest conditions. Note that even the intake valve in #3 is showing signs of running hotter than the others. Interesting because cylinder #3 shares the intake runner with number 4. Cyl 1 and 2 exh. valves are darker gray, cooler running valves. I would expect more consistency in a port injected engine between the exh valves.
Look hard at the intake manifold for leaks at the head near 3 and 4, and check the vacuum port (whats hooked to it) for leaks. Since you have a distributor be safe and check ign timing also.
[ September 24, 2004, 09:56 PM: Message edited by: tpi ]
