Hi again,

Ive got an interesting problem. 1987 Montero 2.6l. Just rebuilt (for reference)

Every morning that I get on the highway, once I hit about 55-60, it feels like I lose a cylinder and it starts to make a pinging noise (or clicking/rattling/etc). At first I thought maybe the advance mechanisms aren't working properly, but I went through and cleaned/greased the mechanical advance, and also checked the vacuum advance. Both seem to be working normally... The timing is set to 6 degrees BTDC.

When it does this, it's only when under load AND at speed (getting on highway, going up a hill at 50mph+). And when it happens it's very sudden, and feels JUST like one cylinder is just gone.

To remedy it, I simply pull off the side of the road, let it idle for a minute, and it drives normally.

Plugs are new, wires are new-ish, cap and rotor are new. I'm wondering if maybe this could have something to do with a jet valve or something.