I cant think what about the steering system would have any effect on engine power, but then I cant think what would cause power loss on right hand turns either.
If I had the problem:
I would try connecting a vacuum gauge to the intake manifold, and bring the hose up from the hood and have the gauge under a wiper blade where I could see it, and try cornering, while keeping track of the vacuum.
Also, its not too hard to uncap the schrader valve on the fuel rail, unscrew the inner stem, and clamp a length of 5/16" fuel line over it; with the other end of the fuel line fitted onto a pressure gauge, which I would also prop on the windshield under a wiper blade. This would tell you if the fuel pressure was consistently adequate & was the same on left and right hand turns.
While I havent had this problem YET, I always expect that any problem an Escort owner has could visit me tomorrow. So Im interested in the cause & cure.