I don't use a hook or smaller needle for k/p3tog, but I don't have a tight tension or gauge. However, there's a lot of ways to hold the yarn and needles without making the sts so tight it's hard to knit into them. And if you wrap the yarn backwards for a purl stitch, that can make them too tight to knit tog through the front legs. Are your stitches twisted, Lizars?
sue- knitting heretic