vestax

just got my car back on the road after 4 months and i got a few problems.
firstly before i had the accident the car was overboosting and fuel cut was kicking in only when she was hot, but i never got the check or cure the problem. now its back on the road and had to have a new maf sensor as the old one was full of water, i'm wondering if that was what was causing the problem, as it aint done it since fitting the new maf.
i was also told the boost solenoid could need checking/cleaning, is there any way of temp bypassing it 2 rule it out?
and is it worth fitting a electronic boost controller and bypassing the orignal

new problem, i start the car it idles fine for 30 seconds then drops down, after a minute or two the idle dips once or twice then it cuts out. starts straight away then does the same again. any ideas??

also whats the cheapest way of having an external wastegate? i love the sound.