Check the connector to the fuel injector. Make sure it is on tight. Look inside the connector and make sure the terminals haven't slipped out of position.
What does the spark plug look like after it's been run a little while? Wet & smells like gasoline? That'd say the injector is firing but fuel is not getting ignited.
Have you checked valve clearances? Peek in via the spark plug hole and verify that the valves are opening & closing.
Could be a minute crack in the distributor cap affecting the post for #3.
How old are the plug wires? I had a problem once (with old wires) of 'cross-fire'. Ignition wires running parallel can induce current in the other wire leading to misfires. Try removing the wire to #3 from the wire holder at the front of the cam cover and temporarily routing it away from the other wires.
A compression test (and leak down test) would help let you know if the problem is inside the engine or not.
edited to add: always check for intake air leaks and vacuum leaks. Sometimes they can leak in such a way as to affect one cylinder more than the others. Also check the plenum to intake boots (short hoses).
What does the spark plug look like after it's been run a little while? Wet & smells like gasoline? That'd say the injector is firing but fuel is not getting ignited.
Have you checked valve clearances? Peek in via the spark plug hole and verify that the valves are opening & closing.
Could be a minute crack in the distributor cap affecting the post for #3.
How old are the plug wires? I had a problem once (with old wires) of 'cross-fire'. Ignition wires running parallel can induce current in the other wire leading to misfires. Try removing the wire to #3 from the wire holder at the front of the cam cover and temporarily routing it away from the other wires.
A compression test (and leak down test) would help let you know if the problem is inside the engine or not.
edited to add: always check for intake air leaks and vacuum leaks. Sometimes they can leak in such a way as to affect one cylinder more than the others. Also check the plenum to intake boots (short hoses).
. So, by now it doesn't matter if it's a burnt valve or head gasket, either way the head needs to come off, I'll go out later and re test # 1 & 2 with a little oil to see if there's any change, there may me but I hope not much 'cause I don't want to go too far into the motor.
