'70 D-jet runs terrible cold, great when warm,, Please share your wisdom Options

[Porsche Rescue]

Car starts when cold (not quickly, but it does start, air temp. 80 degrees), then it is a bitch to keep it going. Once on the road and warmed up it performs beautifully.

I have checked the Aux. Air Valve and it is sucking when cold, plugged when hot.
I replaced the head temp sensor even though the old one tested OK. The new one helped a little, but not near enough.

I have studied Brad Anders' site and can't come up with any other ideas of what to check. I have to believe the ignition system is fine because it runs so well when warm. I have checked timing and dwell and they are on spec.

Any suggestions out there?

[r_towle]

I will run down the issues that it could be.

The ECU has an idle circuit that only engages if the TPS is porperly adjusted. A poorly adjusted TPS will give you a more responsive upper end RPM range, but it will require you tap the gas pedal to keep it at idle.
So, it can be the TPS...I will add a pic to show you how the TPS MUST look at idle.

The Decel valve...mine is removed, no difference.
AAR, mine is removed, no difference.
I live in the northeast...it gets damn cold here, runs ok without either part.

Valve adjustment.
If your valves are too loose or to tight it changes the valve timing and it also creates vacuum leaks..makes it impossible to get the idle correct.

(For this section, unplug the multi spark unit and wire up the distributor correctly for single spark...)
Point gap.
The dwell needs to be set to perfection on these cars, a little bit smaller (a larger dwell period) will provide a bit better burn, but your mutli spark unit will do this also.

Timing.
This needs to be set third...dont be lazy..do the valves, the the point gap/dwell, then the timing.
The timing changes with both of the previous items, so it MUST be done last.
Get the right plugs in there...though the multi spark unit works well with the 4 pronged platinum series plugs...quite nicely actually.

Now, reconnect the multi spark unit.

Vacuum leaks affect Idle.
Remove the intake runners and reseal them at the head.
There should be head---thin gasket---phenolic spacer---thin gasket--intake runner.
I put a small amount of liquid gasket on all surfaces...it helps seal this often overlooked vacuum leak up tight.

Rubber boots between intake runners and plenum.
Clamp them tight..they leak after 35 years.

Clamp all other vacuum lines.

If its still acting up, remove every single vacuum line from the plenum except one..the MPS.
Get rubber vacuum line caps at the parts store and close up all the holes in the plenum..do a very good job and make sure they are tight.
this includes the one or two little hoses that go from the throttle body to the distributor, cap them.

Make sure when you cap them you have no hoses...dont be lazy...get the rubber caps and do it right.

It should run perfectly.
At this point, add one vacuum line at a time..drive it and then let it idle...you will find the faulty part.

So,
TPS is first, adjust as pic shows at idle, flap closed on throttle body.
Valve adjustment
point gap/dwell (Multi spark unit unplugged)
Timing (multi spark unplugged)
Reconnect multi spark.
Reseal all vacuum lines on motor, including intake runners.

Rich