Vauxhall Signum spanner @ engine light . limp home mode

After 3 weeks of happy ownership of this 'mint' 75k mile example I now have the engine management 'problems' I'd heard about and hoped I wouldn't get ! . 3 owners stamped service book , old MOTS , invoices etc . Week ago having started and driven 5 miles on flat road , accelerating uphill in 3rd at 3000rpm I noticed a hiccup and suddenly spanner light came on and it seemed to lose power . I pulled into layby , idle was fine and other obvious things too . After stopping engine restarted fine and spanner disappeared . I drove 30 motorway miles fine but with doubt in mind . Some hours later on return journey everything seemed fine again until about 3000rpm and spanner light came back on and I noticed engine wouldn't rev past 2.5k .

I took the car to local garage whose diagnostics only returned emissions fault . He suggested changing fuel and air filter which were dirty as it turns out ( I'd bought the car from a trusted dealer who MOT'd the car and did oil and filter change in deal ). This seemed to make engine bit smoother but next day spanner came back on . Garage plugged laptop in again but only found emission fault . They suggested go Vauxhall for Tech 2 diagnostic check . Luckily I have experienced garage owner friend in neighbouring town who has this . Tech 2 suggested MAF / EGR / Wiring . From voltage tests whatever and from work on previous cars he suggested MAF was culprit . Intermotor MAF sensor was fitted but seemed to be faulty as read open circuit , replacement part seemed to settle in and many repeated stationary starts and revving to 5000rpm did not bring on spanner light and computer showed no faults or pending faults . Frustratingly driving mile or so engine light came on this time and again engine won't rev above 2.5k . Starting and everything else is fine though .

I'm back in tomorrow and plugging into Tech 2 . He suggests perhaps trying genuine Bosch MAF sensor or perhaps other faults will turn up . Any suggesting anyone before I seek out another local 'wizard' who supposedly fixes these problems all the time . I do hope it's not one of those common known but recurring problems as I actually think it's a great car .