Spent two days diagnosing a no spark symptom on a 1997 Baja Islander 180 with Mercruiser 5.7L Alpha 1 setup. Motor and ignition is all factory/stock. Went through the flow chart for TB 5 and ultimately pointed to bad ICM. I changed out the coil, plugs, wires, cap and rotor just because it was all original and figured I could do a tune up so ideally I'd like to just replace the ICM but I see they are hard to find and pricey. The other option would be to upgrade the ignition system. The DELCO EST is on backorder but it appears that's the most popular upgrade. Any thoughts on other options?

Agree if TBV is not an option I would go EST

est,s will perform better theres no box or ecm just a dist and coil you want external coil est theres tons everywhere try amazon or ebay

Thanks! Ended up going with the EST. Overnighted it last week and it fired right up. Beautiful thing.