CEL P1128 P1130 persistent

[puravidabahia]

hello...i'll try to keep this concise; 2001 Boxster at purchase 105Kmiles; CEL P1128 P1130; replaced MAF Sensor twice as CEL with same codes; occurs mostly while idling at intersections; replaced O2 sensor, fuel pump; oil separator, cleaned throttle body housing; spark plugs; gas filler cap; same result; **at every fillup the vehicle initially fails to fire, only turns over with no ignition; after several attempts it fires but runs very rough and stalls until after driving 1/2 mile or so and then OK, however, CEL continues to come on after clearing

Any thoughts, suggestions?

thanks