420 SEL Timing
I added a new shim a got the clearance correct but no improvement in operation. The idle surges from 200 - 300 Rpm to 1000 Rpm where it smoothes out and then repeats the pattern but not always cyclical.
Does the CD for the 126 cover the 4.2L engine? I have the paper manuals but not the engine manual. Would be nice to have a troubleshooting "tree" to work thru.