1984 Other Chrysler Models daytonturbo

Engine Performance problem
1984 Other Chrysler Models Front Wheel Drive Automatic 60,000 miles

under normal acceleration, the car runs fine but under
moderate to high accelaeration or climbing a hill, the vaccum boost goes into red zone. My mechanic has checked it with his diagnostic tester and it reads code 46 but gives no indication of what is wrong or the fix.
Any ideas