I have a S 1.5 205 8v, still reasonably fresh (~<30k), decked, cam, 3 cut seats, 10.5 compression.
Unfortunately it has never run with the standard ecu, hunting idle (when it used to idle), flat spots, chokes with on/off throttle, pings up any hill <3000rpm, fuel smoke at cold start - ffs the list goes on (makes me wish it had points and carbies *sigh*, never thought i'd say that)
it has been to a reputable mechanic several times, even had the jetronic swapped for motronic with reportedly worse behaviour and supposedly all sensors replaced...
It has blown a head gasket, my thoughts are that a pretty fresh engine shouldn't do that, perhaps the poor timing has caused extra pressure on a reasonably high comp engine and done it.
I need a quickish solution to this as it is my daily. i am thinking of trashing the harness as much as i can and dropping in a haltech sprint, possibly with just cleaning and painting a bit of silver on the deck, adding a 2 ftlb's to the head bolts over stock with a new head gasket. Probably seems dodgy but i cant imagine how such a freshly decked head should need skimming again and i have had considerable success with such cheaty measures in the past (60,000km without an issue.)
oh and apart from when it blew initially it hasn't overheated since. (EDIT: cause i fill it with water before every drive - lol)