1990 Pickup with idling problems...

[Lee280zx]

I have a 1990 Pickup 4 cylinder with the 22RE engine and automatic transmission. It has just 42,000 miles on it. It has been tuned up recently.

The problem I'm having is that when I'm idling with the A/C on and my foot on the brake, the engine idles very roughly, like the RPM is going up and down.

If I remove my foot from the brake or turn the A/C off, the problem disappears immediately every time.

I'm thinking this is some sort of vacuum issue since both the A/C and power brakes have vacuum components, but I would like some ideas about what to check.

Does anyone have any advice/suggestions?

Thanks

[texas12]

I got a '86 4runner, 4 cylinder with the 22RE engine and automatic transmission. They should be pretty close. On top of the valve cover there is a solenoid (1 plug, 2 hoses). This energizes when the a/c is turned ON. Goes to a diaprahmed valve (4 hoses) mounted on the intake manifold. This valve has a plastic screw that will adjust the idle (out is rev up) when the a/c is ON. Make sure the solenoid is energizing when the a/c is turned ON (you can feel the click) and check the associated hoses for splits/leaks.

[brokentoy]

cheack your vaccum lines for any craks , weather checking, or abnormalities, i recently set the overhead on my 94 22re and it did the same thing. forgot to plug in the vacuum lines to the power steering pump