That makes sense thank you for all your feedback. All suggestions are welcome if you can think of anything else please let me know

LS9 swap?

Is that the series 2 not sure what the LS9 is

LS9

https://www.chevrolet.com/performance/crate-engines/ls9

Only $20,000. For an additional $5000, you can go down to Bowling Green Kentucky and hand assemble the engine yourself.

Too rich for my blood I'll just stick with my old beater

Mike, now I know what you can get me for Christmas.....Thanks in advance!!!!!!!!!!

I hope you didn't replace the cam and crank sensors for this problem.....

This should be treated as a misfire.......

Also with this kind of mileage, you should be checking compression.......

So first I would remove the wires one at a time from each coil terminal, look for carbonning or corrosion on the terminal.....if present., sand clean the terminal(*), and replace the ignition wires.....then I would also do a coil output test at the end of each ignition wire with a spark tester....if ok, then test drive....



If roughness is still there, I would then use a can of carb cleaner and spray in spirts, around the intake manifold vac lines, etc., looking for a change in idle......if nothing shows up, then I would remove the plugs, and look for plugs that may be fouled, affecting a particular cylinder....and while the plugs are out, with this kind of mileage, I would be doing a compression check...also you replaced the plugs 2 years ago, did you use OEM?

If this checks out, I would remove the O2 sensor, to see if it is contaminated(usually coolant) or carbonned up(car may have been running rich for too long)....

If we stil have not come up with something, I would be checking injectors for even flow.....

You say it does not run rough at first, only after warmed up? Does it run rough at idle, or only under a load on the highway?

Also, when out on the highway, and you lay into it, does it accelerate ok?

I agree with what Tech II said. Personally, at that many mioles if it hasn't had wires replaced in the last 80,000+ miles then I'd replace wires first and see if that clears it up. Also as Tech II said, what kind of plugs? Had a friend buy a `98 LeSabre running rough, swapped out crummy Autolite cheapest plugs they could find for ACDelco Iridum plugs and it cleared right up. Then I did wires because the ones that came with it looked factory and the car had umpty-someodd-bazillion miles on it.

LOL would love to see (while cringing) what the 4T60E would do with that.

Only under a load

Definitely sounds like secondary ignition......

And how many miles on the plugs you put in?

sometimes the simplest solution can make all the difference.