Chainsaw Repair

Tough to answer questions like this when it's on someone elses bench and you can't hear it yourself. No idle is usually one of 2 things. Loading up; meaning too much fuel. Or running out of fuel; leaning out in the idle circuit on the lo side of the carb. If not the carb itself, an air leak on the intake can cause this.

But in this case, I suspect the top end from Amazon may have burned up already.  If all was well when it left your shop and the problem appeared when it shut down after it got good and hot, first thing I'd do is to check that cylinder/compression first. If it's OK, then we can look for carb or air leak problems. Always need to know why the original cylinder failed before replacing a top end. 346/353 bottom ends rarely have issues ; it's almost always intake/fuel related.

I'm assuming here that you used an inexpensive top end, not an OEM one from Husky. Sometimes they work, sometimes they don't. An OEM 346 kit only costs about $110 and bolts right on a 353 with no other changes.