Hi,
1994 Buick LeSabre 3800 engine 148,000 milesEngine misfires/chuggles at part throttle and light load (about 60 mph). Has good acceleration/performance otherwise. P1406 History code. Scan tool shows EGR Actual % swings wildly when the chuggle happens but the EGR Desired is steady.. Engine runs great when EGR is unplugged. Tried a new EGR valve and it didn't fix the problem. Intake manifold vacuum is high and steady when EGR is disconnected. I could use some suggestions!!!!
Thanks,
Ron