LS400 Bogs bad at 3.5k RPM+

[trot]

I have a 1990 ls400 220k miles and when ever i give it gas it bogs very bad usally around 3.5k rpm-4.2k rpm. sometimes it wont bog for a while but will start after driving for a while, if i rev in neutral or park it will rev perfectly to limiter im just confused on what it could be ill add a video below. i was thinking maybe fuel filter im about to do it tommrow and see but im not really sure any help is appreciated

[Jeremy M.]

Start with the basics and check battery connections are clean and tight. After that, checking both fuel pressure and fuel flow is a good idea. If it has a rough idle, you can start by checking your ignition system (spark plugs, wires, as well as the distributor caps and rotors). I'll preface this with a disclaimer that it's a guess, but from your description and the short video, it sounds to me like a throttle position sensor may be reading incorrectly at times. You'd need to test your sensor and see if the signal drops out or jumps around on the output of the sensor; as you slowly press on the throttle, you should see a smooth progressive change in signal. I believe there are other posts about checking and adjusting a TPS for your model year, but I won't try and go into detail myself, as my vehicle is a completely different system to yours.