Stumble on acceleration

2005 Legacy GT ~80K miles now.
I purchased the car used in 2008 Feb with ~28K miles. It had a slight miss at idle. Service shop said this is normal for Subaru's. As it was my first I accepted this.
Summer of 2010 I began to get CEL calling for Cyl 1 misfire.
I did much reading on diagnosing and solving the problem. With that, I ran a fuel injector cleaner regimen with no effect. I checked all sensors and cleaned the MAF with no effect. I then swapped coil packs between cylinders and did a compression test. Compression was ~145psi across all cylinders. With no change in CEL frequency, everything above pointed to a bad fuel injector. I then replaced all four fuel injectors. With this, the car now idles normally, purrs like a kitten at idle. But, with the fuel injector change the car now stumbles on acceleration. It ran fine, short of idle miss and CEL, prior to this. Seems to accelerate normally when cold but once warm, it stumbles on initial acceleration. The stumble is very similar to a bad accelerator pump on a carbureted engine. I've looked for a vacuum leak in the intake system with no luck.
I'm out of ideas and open to other input to bring it back to normal.