2000 Other Toyota Models High idle problem

2000 Tacoma 3.4 V-6

When started idle, goes to 1800, then slowly drops to normal. Usually takes 4-5 minutes. If you don't wait that long and start driving, at 30 mph, the rpm is 2000 (seems like it doesn't want to shift). After a few minutes of driving once the engine warms up, idle returns to normal. I'm only getting 200 miles a tank, and it smells rich. I have no check engine light. I have changed the Throttle position sensor, engine coolant temp sensor, and idle air cont valve. MAF sensor and throttle body have been cleaned as well. At 30-40 mph, you can hear the exhaust surging, but no rpm fluxes on the instrument panel.