Nitro fuel...
 

didn't run my nitros (Monster GT & Mugen MBX-4 XR) for about a year.
Is it possible that the fuel went bad in this time? closed containers & no leak
(slight overpressure in the containers)
Somehow I have tuning problems with both the CMB Rallye LSi 3,5cc
and the Picco P3 4.6cc
They fire up and run but as soon as I give more throttle they stall... :confused:

It's likely the fuel will have gone off after that amount of time. Get yourself some new fuel, and I bet they'll run better.

Also remember, if they haven't been used for ages, the tune is probably going to be off.