EdMcK515,
Unclipping the 4 clips will not be enough to get the old air filter out and the new one in. Take a look at the large, round, black plastic tubing that comes in on a diagonal to the air filter housing. About 3 or 4 inches from the housing, on this tube, you will see a silver clamping devise that goes all the way around the tube, and has a long bolt that is used to tighten or loosen this "O" type clamp (there's another one farther up this tube, about another 12" or so). Loosen this "O" clamp (the one closest to your air filter housing). That should now give you enough play to lift the top of the air filter housing out of the way, get the old air filter out, and the new one in.
If your old filter is all clogged up, this replacement should make your mileage go up, cause a clogged air filter starves the engine of needed oxygen for the piston firing, and makes the whole fuel burning process very inefficient.
MXVR4
Holland, MI
1996 ES 300
73,000 miles