DIAGNOSIS: Yeah, this one's common. The dryer heats, so the element is working. The most likely culprit is a clogged venting system—either the lint screen housing, the internal duct, or the external vent line.
FIX: Start with the easiest: clean the lint filter with warm water and a soft brush. The mesh can get clogged with residue from dryer sheets. Then, unplug the dryer, disconnect the vent duct from the back, and vacuum out the outlet on the dryer itself. You'd be amazed how much lint gets past the filter. Finally, check your external vent cap outside the house for blockage.
IF THAT DIDN'T WORK: The thermal fuse or high-limit thermostat might be tripping intermittently, causing the heater to cycle off too early. It's a safety part on the heater housing that can fail and cause weak heating.
HEADS UP: Never run the dryer with a severely clogged vent. It's a major fire hazard and can also overheat and blow the thermal fuse, which will require a part replacement before heat works at all.