1988 isuzu trooper " 3 cylinder "?

Had a new head installed a year ago truck ran great then one day driving down the road the truck feels like its on 3 cy, spudders spitz and dies. does NOT overheat, blow anykind of smoke tick or bank. What would cause me to loose a cylinder on a 4cy fuil injected trooper. I going to do a compression test latter this morning and if all cylinders are were they should be WERE DO I LOOK THEN. Thankyou.