1988 Honda CRX Engine Jerking

Engine Performance problem
1988 Honda CRX 4 cyl Two Wheel Drive Manual

Completly rebuilt engine 1.5. Engine runs good most of the time. When going down hill, the engine bucks and jumps like it is running out of fuel even with a full tank. If you open the throttle up it will smooth out. I paid 210 dollars to a mechanic who put a sheetmetal blocking plate to block off the EGR valve. This helped but it still jerks when I go down a mountain or come to a stop light and start to take off again. Seems to run good on the freeway. I wonder if I might have got a vacuum line under the manifold out of place? Thanks