Still rough running...more

[ToyoTribe]

Our 94 Tercel still runs rough when it's fully warmed up. When it's cold, it is not bad.

It smokes at low RPMs.

Cylinders 2 and 3 stay wet, apparently with unburned gas. The plugs in 2 and 3 get fouled pretty badly.

There is not much power at low idle.

Is the screw on top the only way to adjust idle?

It gets 17-18 mpg.

Could this be a head gasket problem?

[NickR]

The srew on the throttle body is the only way to adjust the idle that I know of.

It could be a head gasket. You need to check the compression. If the compression is good, it's not the head gasket. If the compression is low on cylinders 2 and 3 that would strongly suggest a bad head gasket (though it might be piston rings or valves). If the compression is bad, squirt a teaspoonfull of oil into 2 and 3. If the compression rises, it's the rings, if it stays low, it's the head gasket or valves, so you will need to remove the head anyway to check.