Has anyone used Presto pots for melting plastisol? Will it hold the temp.

I have not.  I have used a lot of methods and have settled on a microwave and nor pour silicone cups.

I only use presto pots for big batches of remelt. For virgin plastic I still use Pyrex in the microwave.

Presto pots work fine for large batches. I prefer ceramic coated cast iron pots on a hotplate. You can buy them used on ebay for a reasonable price in any size you want. They work great. Nice even heating and easy cleanup.