I have a 73 1.7 with the 1.8 big bore. When first started it idles at about 2k then drops after 2mins and will very in idle between 1500 and 200, and drives rough until the head temp is around 350. After that it runs great and idles around 900 and 1k, if you park long enough for it to cool down it rough until hot again.

The engine is totally redone, I have checked and rechecked everything. The entire motor and everthing on it is with in specs.

Any help would be great, as I have run out of things to check or try.

does that include the cylinder head temp sensor to the FI, and the Auxilary Air Regulator ? because those are two of the most common things that can cause those symptoms ...

Everything and I mean everthing! Has been checked and rechecked.

Well there can't be a problem then...