LHS help from a Chryco tech....

My '97 LHS has a miss. 3.5 V6. Engine's in good shape, even comp across the cyls, uses no oil, plug color looked good etc. Has about 95,000 miles, been garaged/pampered since new. Had a little putter at idle to begin with, has progressed to a noticeable miss under load. Gas mileage has dropped 3mpg {27 to 24} and the torque is down too. Lost it's pep.

Had to replace the injector O rings, so while I had the upper plenum off I replaced the injectors, plugs and wires, as these were all OEM. Still had the putter at idle. It soon progressed to a miss under load, I then replaced the coil pack as well, to no avail. I can find no vacuum leaks. I can feel the miss at idle in gear now.

I have an old SnapOn scanner, has no codes. By initiating an injector kill test the putter disappears, smooth as glass. This is open loop, correct? Any suggestions where to look next?