Hey guys.
Need some help. My car wouldn't start the other day there and narrowed it down to the fuel pump and or relay. Have changed both. The pump is from another subaru which is a good bit bigger than the 1 that came out. Can't remember the codes on the stickers. But got it started and when on boost it's stuttering and jerky. And the car just doesn't feel right.
Anyone had this before and what's the cause.

Thanks in advance