Need some ideas on this car it came in with broken cam belt. Removed head had all new valves and guides fitted refitted head then mot tested car passed emissions. I noticed when driving a slight surging between 1700 to 3000 rpm. cleaned throttle body/ egr and re adapted it with no change, gave it back to customer to see if it would set fuel trims.

So a month down the line still there customer said it was not there before i carried out the repair. There are no fault codes. A multiplicative fuel trim of + 5. in desperation i fitted new map sensor new wide band o2 sensor new coil plugs and leads. The short term fuel trims go from +2 at idle to -3 at 1800 rpm then plus 7 as it gets over 2500. Smoke tested at inlet and blocked tail pipe to check for leaks and there are none. Driving up hill it almost feels like a miss fire. The surge is not so apparent in 4th gear as the load is greater i guess with injector duration over 12 ms. Fuel pressure is 45 psi at open throttle and 35 psi at idle flow is 2.5 liters a minute down to 2 liters when driving hard on the road. The surging is there right from cold but is more defined when hot. Compression are all over 175 psi with throttle body removed for max air inlet manifold vacuum is good at idle and steady when driving. I have scoped plug kv secondary pick up but it just seemed to confuse me further. I am going to send injectors for flow testing next week. Sticking my head up waiting someone to shoot me down but i have run out of ideas. . Any help with it greatly appreciated.