1998 Buick Regal Cylinder 6 misfire
hello I have a 1998 Buick Regal 3.8 vehicle having ahesitation rumbling in idle and in DriveI replace the spark plugs and ignition wires I've even taking out injectors and clean them all out I swapped cylinder 6 injector with cylinder 4 injector to see if the problem will correct I've checked all the electrical going to the injectors it's working fine I've also did a compression test Cylinder 6 has 150 pounds of compressionI also swapped the coil pack for Cylinder 6 and replaced it with a new one and is still hesitating a fuel pressure test was done it's showing 45 pounds which is good indication fuel regulator is working fine there is no drop in vacuum when hose is disconnected I've also swapped spark plugs and ignition wires with Cylinder 6 to see if the problem will correct and still no luck hesitation still there also I forgot to mention in the beginning that cylinder 3 was the one with the problem when I took out the injectors and clean them out it jump to cylinder number 6 then put everything back did a road test and came back random misfire and then clear the codes to the computer road test again and came back cylinder number 6 misfire this vehicle is driving me crazy but I'm not giving up can you please help with any suggestions what might be the issue thanks in advance Louie .
do you have a scan tool?does misfire more worse when engine is cold?if so could be a intake gasket that is cracked that is causing a vacuum leak a lean condition.take a plastic spray bottle filled with water and adjust a stream of water and spray on intake and listen for rpm change and a sucking sound.