Hello all.

I have a 98 GS400 with 54K on it. I have had it less than a month. I test drove it for 1.5 hours and it ran great at all speeds. After I committed to buy it, the independent dealer changed the oil & filter and maybe the trans fluid. They claim they do this on all vehicles. They actually brought the car to my house after they took care of everything. The first night I noticed that the air filter housing was unclipped and investigated. The air filter was missing. Apparently their mechanic had ordered a new filter but didn't put it in prior to the salesman delivering me the car. I know the old air filter was in the car because I checked it’s condition after my test drive. The car could have been driven w/out a filter for 12 or more miles.

My car now lugs or misses occasionally while traveling at 60mph or higher. It only seems to do it in 5th gear. Since I rev the car out in first and second gear with out a miss, I feel it is probably not ignition or fuel related and I am starting to question the trans. In fact, the car is so silky smooth when cruising around in stop and go traffic that I often forget I have the problem till I get on a highway.

At what speeds should a GS400 go into 4th and 5th gears in a normal cruise situation? I read a thread about Toyota specific trans fluid. I have driven the car less than 1000 miles. If the wrong fluid is in the trans, what are the symptoms and would they occur that quickly? Since I don’t seem to have this problem in other gears or all over the rpm range, I am thinking that driving without the air filter is not the problem. I certainly could be wrong. Short of taking it to a dealer, is there any other things I should check that are relatively easy?


Thanks,

Neil