I have a 1997 Buick Lesabre Limited with a slight problem..I've replaced all three coils, new plugs and wires..The engine is a 3.8 V-6 series II..Upon acceleration, mostly, it shakes and hesitate

SOURCE: 1995 buick park ave bucks/shakes

it may be fuel injector wiring. since you have check the compression and the replaced the injector. it is time to take a look at the injector wires.

SOURCE: buick lesabre no start

Hi you have replaced allmost everything ,(try fuel pump relay)

SOURCE: buick lesabre nightmare

Need to get a scan tool and look at the data stream while it is running for alot more info.Also any trouble codes.Sounds like initially,the engine isn't getting any fuel.I would have a pressure gauge connected to the fuel rail on the engine,so i could monitor the fuel pressure while all this is going on.Items to look at on the data stream would be timing,what timing is the PCM commanding for the engine.Also,have you checked for continuos power feed to the coils during this no start condition,and fire at the plugs while cranking.You could possibly still have spark,but maybe it is extremely weak?I have seen bad ignition switches cause weird problems before too.Many things power up through the ignition switch,just a thought.Have also seen bad PCM's cause strange problems..38 volts is a little on the low side for GM.Usually see those at,at least .50 and up,and rise steadily while pressing the throttle,up to just under 5.0 volts.Potentiometer with 5 volt supply.Vacuum leak can be checked with engine running at a steady idle speed,spray brake cleaner all around the intake manifold and listen for engine speed change.

SOURCE: Hesitation during aceleration

You may have a vaccume leak

SOURCE: 1997 Buick LeSabre, 54,000 miles

remove plugs and check for carbon tracing . if found plugs and wires will fix problem