2 stroke 25hp tohatsu problems

[gadwall88]

I have a 2004 2 stroke 25 hp tohatsu that had been running great all spring then one day when running to go catfishing it just flat gave out on me. Was running full throttle and it just killed, there was no slow down and die like it was running out of fuel, just a hard kill like the kill switched was pulled. After it killed I was able to get it started at it rev'ed up in neutral but it would only let me idle in gear for a little while then kill hard again.

I went by the mechanic and got the engine's compression checked and they both had full compression. After checking that the mechanic told me he believed it was overheating and to change the water pump and thermostat. Well after doing all that it got better I was able to get on step again but only for about 10 seconds and it killed hard just like the first time.

I don't know what it could possibly be but the mechanic still thinks it could be a cooling issue. I was wondering what the boards opinion is on this debacle and if anyone could give me any suggestions on what to try next.

P.S. the gas has the correct oil mixture and the lower unit has oil but hasn't been changed in about 6 months.

Thanks