I got a new gas stove and my tried and true recipe for English toffee is turning out sugary and gritty, not smooth and crunchy. Same with my fudge.
You'll probably love your gas stove once you get used to it. Did you have electric before or just a different gas stove?
Either way, it's really not the stove, per se. It's either a temperature issue in cooking the mixture or a humidity issue in the weather.
If it IS humid, you may need to allow the candy to cook longer up to 2 degrees hotter. But, don't overheat or that will also cause it to get sugary.
When stirring, stir consistently and gently. If sugar mixture gets up the sides of the pan, take a pastry brush and hot water and brush the sides of the pan to get the sugar back down into the rest of the mixture.
If the sugar starts to crystallize, it causes a riot and all the sugar wants to crystallize. So really keep an eye on any sugar crystals forming on the sides of the pan.
Finally, make sure your candy thermometer is still accurate by testing it in boiling water. It should read 212 degrees. If not, adjust your cooking time as needed.
Hope that helps some. I've added a video below that shows a commercial company making some yummy Almond Toffee. It's a bit long, but I found it fascinating.