What are some symptoms of "Tight Valves" on a 3VZE?

I have taken my p/u to a knowledgeable mechanic in my opinion and he thinks this may be the cause of my problems.

Problems:
Erratic Idle. A skip and shake of the engine without any real pattern too it. I also notice inconsistent exhaust at idle. I went to the back and put my hand in front of it. You get a larger "puff" once in a while without a real pattern either.

Also, a skip at erratic times when driving. Floor it through the gears, no symptoms. Drive normally under partial throttle and you get the skip now and again. Most noticeable at the low rpms/higher gears.

Plugs, Wires, Igniter, Distributor seem to be fine.

Thanks for any input.

ThePlumber.