Rough idle/No tach reading

[EODJay]

This is on a 90SPL J90TSLECM. Motor idles great then a noticeable tone shift, rough idle and tach drops. If you rev it the tach signal comes back; sometimes it stays idling rough with no tach reading and sometimes it returns to a good idle with tach reading. However, eventually the idle always returns to rough. Not sure if it matters but it sheared the flywheel key a while back and the aforementioned started on the first time back in the water after installing a new key. Ay thoughts on what this could be or some good trouble shooting tips?

 

[racerone]

I know some history on these motors.-----I would start with a compression test.----Post the numbers.-----What value did you torque the flywheel nut to ?----Are all wiring connections clean and tight ?----

 

[EODJay]

Compression is 120 on all four holes, the flywheel was torqued to 105lb-ft and all connections have been cleaned with emory cloth and dielectric grease applied.

 

[EODJay]

Any thoughts?