Hi Andrew, I am sorry for your experience. I could not but answer your questions without fealing revolted, so if I sound angry, it is not against you....
First to start, your tiptronic was rebuilt two years ago with 80 k miles with factory parts.
There is no factory parts for the tiptronic, there was a factory policy since 2004 and a TSB issued back then that no tiptronic parts would be available, and the box should be changed as a whole. Less when there were parts for the tiptronic before 2004, it was only a few sprockets and oil seals only.
You had the micro-controller chip replaced.
There is no microchip to replace. There is a module (brain) under the passenger seat that contains an EPROM. This EPROM can be flashed only once. Why?
because RestOftheWorld cars have a different program mapping than the US models. And if a european car was exported to the US, the dealer could reflash the EPROM to the US mapping. This could be done by the factory computer called PST2, porsche system tester 2.
now some aftermarket diagnostic readers can access the cars brain, and if a stupid mechanic reflashes the tiptronic brain thinking he can reset it, he will kill the brain.
These tiptronic brains are unbreakable, undestructable, unless you mingle electronically with them through an OBD reader. No electrical problem could harm the Tiptronic brain.
I bet the mechanics only removed the tiptronic, and changed the forward clutch seal. That is a known issue in these transmissions.
What breaks this seal is the fact that when car is warm, you put the gear knob in Park and you rev the engine. The excess pressure burns the seal. This happens a lot in emission control tests.
To avoid that, when box is warm, you should turn off the engine for thirty seconds to depressurize gearbox, and then run engine and rev only in Park position. If you select any gear, the gearbox will be pressurized again.
Alert tiptronic problem failure very serious please distribute
As for engine rebuilt, if it was running, you shouldn't have touched it. But scrupulous mechanics advise you the contrary...
As for robustness, I honestly had an experience with this. Had an emergency back in 2005, and needed to travel to the middle east immediately with no tickets available for the following days. I grabbed a small back pack and a huge bottle of soda, and took the 993. I drove 34 hours continuously and crossed 10 countries. 4205 kilometers from constant 250 kmh on german autobahn through two feet mud roads in Serbia Croatia and Bulgaria etc.
On my arrival, I only washed the car.
In fact it was so reliable, I redid the trip the next year willingly
Now for solutions, please note that tiptronic rebuilt boxes from ZF (original builder of the 993 transmission) were $3000 last year. That's good to know as assurance.
where are you located US or Europe, ? regards