Tbi idle is too low.

[DnStClr]

I installed a new distributor, coil, plugs and wires, and can't seem to get the timing and idle right. (87 tbi, 350, 700R4 auto).
I unplugged the EST wire and removed the vacuum hose from the manifold and plugged the hose. Made sure the engine was at TDC with the rotor pointing at 6:30. The engine starts and runs good. When I move the distributor to align my timing marks, the timing light reads 940RPM. I tighten down the distributor at 0 degrees timing like the sticker on the radiator cover says.
After I install the air cleaner and plug the vacuum line and EST wire back in,start the engine back up, and it shows 560 RPM and the timing mark has moved to somewhere around 15-16 degrees advanced. The low idle causes the engine to stall, so I'm wondering about my procedures. Do they look right? On a tbi, should I not unplug the vacuum line from the manifold during timing setup? 

[Russ130]

Does the sticker on the radiator thingy say to unplug the vacumn line? If not then you should leave it plugged in.

[78 Chevyrado]

Yeah the est wire and the vaccum line should be disconnected and plugged.

I can't remember the procedure, but there's way to reset or calibrate your IAC Idle Air Control Valve.  You have to do this when you get a new IAC, but I had to do it a couple of times to my old '87.  The IAC is similar in operation as a mixture screw, it's just a motor that screws in and out to allow more or less air past the valve.  It's real easy to do I just can't remember how.

Another thing could be the timing mark on the balancer is off.  If it's a high mileage engine the outer ring could have slipped on the inner hub.

[Captkaos]

To reset the IAC: Key off for 10 sec start the engine for 5 sec, key off for 10 sec again. Then unplug the IAC and start the engine.

[VileZambonie]

Which vacuum line are you unplugging? Just put the EST in bypass and set the timing to 0°. After setting reconnect the bypass wire then disconnect the battery for 30 seconds and restart the engine.

[Russ130]

You know for the life of me I don't ever remember unconnecting a vacumn line to set the timing on a computer controlled engine. Disconnecting the battery as Vile says will clear any codes that may come up from bypassing the EST.

[DnStClr]

 1. Ok.I'll reset the idle air control.
 2. Yes, I have been disconnecting the battery to reset the est fault.
 3. Well, actually Vile, (now that I look at it better) the vacuum line is one at the rear of the intake manifold right next to the distributor and remote coil. I     
     think it feeds the cruise control.
  I'll attack it again in the morning.
   

[78 Chevyrado]

OOPS  I was thinking to unplug the vaccum hose to the vaccum advance, but the efi distributor doesn't have it, so you shouldn't disconnect any vaccum hoses for this.   

[lawdog49]

not meaning to thread-jack here, but Chris- what does the IAC look like and where is it- i think i need to do this cause my idle has gotten rough all of a sudden.

[VileZambonie]

Square 4 wire plug on the throttle body

[Captkaos]

Passenger side of the TBI looks like a "rocket" with as vile stated a square 4 wire plug.

looks like this: