2000 Sable idle stumble

[fgross2006]

My 2000 Sable has an idle problem.

Sitting in park the idle drops and jumps over and over until the engine stalls. In drive, sitting at a red light, the idle hiccups every 20 seconds or so.

Three years ago I put in a rebuilt crate motor, a new ECM, idle control valve, MAF, O2's, EGR, plugs, wires. The stumble was always there in park even after replacing all the above, but lately its gotten worse to the point that it now stumbles in drive.

Any suggestions what to look at?

[83gt351w]

Walked over to my neighbors house last weekend, and he had the hood up on his daughters CRV. The idle was jumping all over the place. He said he replaced the brake line going to a distribution block in the engine compartment a few days before. He asked if I'd look at it, and sure enough, when he was digging around in the engine bay, he damaged a vacuum line. Replaced it, idle restored.

[fgross2006]

Walked over to my neighbors house last weekend, and he had the hood up on his daughters CRV. The idle was jumping all over the place. He said he replaced the brake line going to a distribution block in the engine compartment a few days before. He asked if I'd look at it, and sure enough, when he was digging around in the engine bay, he damaged a vacuum line. Replaced it, idle restored.

I found a broken vacuum tube for the heater controls. I fixed the tube and now the heater controls work and the idle improved .

[83gt351w]

Boom!