What did your mechanic have to say about oil spurting out when you removed the dipstick?
Also, I think that there is too little evidence, for me, to suspect that the ECU or the TPS is at fault. They don't generally go south from lack of use. Sounds like your dashboard is signaling fault codes.... can you tell us what they are?
The oil spurting is troublesome and suspect, as is the cleanliness of the injector, condition of the valve lash, and your electrical flow ....starting with battery cables, spark plug cap and grounds to frame.
Most suspect is the massively overfilled engine oil.
Please give further details about that.
Stig