my mom's van had a problem similar to that it would run in the normal on the temp gauge but there was not heat. we replaced the termostat, waterpump, radiator cap, and coolant. finally we took it to nissan (its a 99 quest, very fast for a van too) and the went to work on it and it turned out to be some leak that was underthe intake manifold and to get there they had to drop the motor out it was expensive to do but hey no she has heat. so i would check your coolant level, waterpump and thermostat first then go into more complicated things

98.5 Black SE ATX S&B filter, SVT MAF, optimized SVT TB, mesh grille, removed orange reflectors, painted rear reflector, gutted pre-cats, optimized SVT LIM, 19lb injectors, resonator removed cant afford an svt but lookin for 1 in nc