Engine has eratic idle and lurches after it.

Engine has eratic idle and lurches after it warms up (20 minutes). The Ignition module was replaced 20,000 miles ago. This is a follow up to my original question from September 6, 2012.
Here is what I've done on the car since then.


1990 Ford Tempo (4 cylinder) Today’s date Dec.11, 2012
2.3 L - manual transmission
VIN # 1FABP35XILK234531
Odometer – 245 270 km

Vehicle in trouble since Sept. 6, 2012

Thanks for the initial comments.

I can’t take it to a pro as that is not a financial option for me. I would be prepared to pay 20 dollars for some advice that allows me to know what the problem is, so that I can fix it myself.
I can reproduce the “lurching” referred to on September 6 – 2012. It seems to only occur after about 20 minutes of running (either by driving it or letting it idle). The lurching, once it starts is quite persistant and eventually will lead to a stall unless I use the gas pedal to keep the RPM up while stopped. I thought I had the problem solved when I presumed it must be temperature related. This presumption pointed me to the cooling system and I found that; a) system not holding pressure b) rust colored antifreeze observed though Radiator Cap c) thermostat may not have been working.

I have since;
1) replaced a leaking hose (thermostat to heater hose- toward firewall)
2) replaced thermostat and radiator cap
3) Flushed the system quite a few times with water and also with “Prestone super flush”(the rusty liquid had gel-ed in the antifreeze reservoir so I thought it important to repeat the flushing)
4) Engine Coolant Temp. (ECT) sensor changed.
5) Replaced the Air charge temperature (ACT) sensor in the intake manifold.

Basically, I have made sure the system is being cooled properly
[ thermostat opens when warmed, and results in the cooling fan turning on (fan switch works). Also the water pump is working as I feel the pump pressure when I hold the upper radiator hose], Yet the problem persists.

I have redone the Trouble codes test.
Two outcomes result; they now show the following;
1) if I perform the test prior to 20 minutes of idling.

“0” or (Key On Engine Off ) KOEO codes;
11 - system Ok

“C”(continuous memory) codes;
14 - Ignition profile pickup is eratic

“R”(engine running) codes;
11 - system Ok

If I perform the test after 20 minutes of idling,
the Trouble codes show the following;

“0” or (Key On Engine Off ) KOEO codes;
11 - system Ok

“C”(continuous memory) codes;
14 - Ignition profile pickup is eratic

“R”(engine running) codes;
Either the code below would be indicated (if engine didn’t stall)
13 - Ignition profile pickup is eratic
and RPM would fluctuate between 1800 and 500 RPM.
Or
if engine stalled, the following code would be indicated
77 - Goose test not performed


If anyone has experienced these symptoms or knows what this problem probably is, I would appreciate communicating with them.
Any information would be helpful.
The frustrating part is that the car works perfectly for the first fifteen (or so) minutes.

Thanks in advance,

Chris