Need help checking / setting timing on 5.7 blue water in 91 skier.

[Nweuroskier]

Have a 91 195 euro skier. Last season installed new electronic ignition and cap and rotor and wires and plugs. Ran good for most of this season except for when slamming throttle from an idle the motor would fall on its face unless I eased it on. But now it started running rough backfiring and seems like a missfire. Never really sure that I got the timing correct in the first place and would to know how to correctly check / set it. I have a light with adjustable advance knob. Its says it needs to be 8 degrees BTDC. I know the basics but don't know where I should set the knob on the light. Where I should try and get the mark to line up on the balancer. Any tips or ideas? Thanks. Might also have an issue with something in the ignition

[Rednucleus]

If it's a progressively worsening problem, timing is probably not the main issue. Was it running 100% normal before your electronic ignition upgrade?

[Nweuroskier]

Yes it ran good before the ignition upgrade was just due for points so decided to upgrade. But it did hesitate off the start under full throttle. But the newest issue that is keeping me off the water that just randomly happened while after shutting it down at a dock for about 20 mins then when leaving noticed a rough idle and shaking under throttle and really load back fire through the carb. Like you said I dougbt the timing jumped something else is probably failing but just wanted to make sure I had it right. I don't know if there is any way to test if the ignitior is having a problem? I'm pretty sure all holes are firing and for sure getting spark. I think the hesitation off the start is carb relatd related and has done it ever since I had it rebuilt 3 years ago. But the rough missing seems to be ignition related?