1986 supra 351W BAD miss under load after warm up

so ive pretty much had this problem for a year now. Once the boat warms up if i put a heavy load it starts to miss really bad but it will kinda clear up after i cruise under little load. yesterday i adjusted the timing and did like 20 out the hole digs and it ran great and only had a very small slight miss so i thought i had it. Here are the things ive done
New cap and rotor
new spark plugs
chaeck timing around 6-8 degs
new water separator filteri have a mallory electric ignition and distributor

also what are the best spark plug wires

thanks

Check your ignition coil, mine went bad and I spent a significant amount of time chasing all sorts of issues that resolved with the new coil.

Are you still running points?

No it’s all electronic

Quote:

---

Originally Posted by Jetlink

Check your ignition coil, mine went bad and I spent a significant amount of time chasing all sorts of issues that resolved with the new coil.

---

Good place to start. Also, has the carburetor ever been rebuilt?

Carb is new just picked up a coil and a fuel pressure gauge bout to slap that on there. What about plug wires what are best?

Quote:

---

Originally Posted by bonomosupra

Carb is new just picked up a coil and a fuel pressure gauge bout to slap that on there. What about plug wires what are best?

---

I used the standard PCM wires all the years I had my 89'. Never had an issue. On my current boat, I bought a set of Standard Blue streak ignition wires from Rock Auto. These were a step up from the stock Indmar wires.

Can you get them from a auto parts store? If so do you have a vehicle to reference for them?

Quote:

---

Originally Posted by bonomosupra

Can you get them from a auto parts store? If so do you have a vehicle to reference for them?

---

I don’t have the info anymore on my 89’. My 2004 takes different wires.

What electronic ignition brand are you running ? Some of the electronic conversion system were problematic.