I have a Whirlpool Dryer model number LEN3634DW1. It does not dry well at all. I have cleaned out all of the lint things, I have replaced the heater element and the hi-temp components. This has only improved performance marginally. What else should I try?

Have you checked the duct and outdoor vent? Is the duct smashed when the dryer is pushed back into place? Run the empty dryer on the no heat setting, does it blow a lot of air out the vent like it should? Are you using approved duct material and elbows? Is the duct (and the duct inside the dryer) sealed and not leaking? Is the duct too long? Is the dryer able to get enough air, in other words is it in a closet or enclosed space where it can't "breathe"? Did you take the dryer apart and check the internal air passages and fan? Is the fan loose on it's drive shaft? After running a load for 20 minutes or so, is the laundry in it pretty warm (heating element really working)? Just because it's a new element doesn't mean that it will heat if something else is wrong in the wiring or controls.

Just some thoughts in no particular order.