I have done the following to try and find the EVAP problem on my 99 RX 300. It is not the gas cap, and it is not the Vacuum Switch Valve. I have replaced both and still have that damn check engine light. I can reset this code by pulling the EFI fuse or disconnecting the bat cable. It usually returns in about 100 miles of driving and again the code is P0446. Is there any cheap way to check for leaks in the vacuum hosing, gas tank, charcoal cannister etc. I have heard of a smoke test is this expensive? Just trying to get that light off it is driving me nuts. Any help would be appreciated.