My 300TE is overheating.

New radiator...Behr.

New thermostat...also Behr.

Zerex ZO5, 50/50 mixture.

New hoses, clamps.

Car starts and runs well. If on the Interstate temp stays at about 90* until we get off the freeway and on to stop and go traffic. Then she starts heatin'.

Off with the A/C...turn on the heater...down she comes a bit. Both fans are on any time she goes over 100*.

229,000 1991 300TE

Water pump changed at about 150,000 at the MB dealer in Phoenix.

Checked all the threads, there doesn't seem to be a water pump test...or am I living it?

Thanks for your inputs...in advance.