Hello everyone my name is Dan i just bought a 1998 Honda Accord v6 vtec 3.0 off someone just last week and I think something may be wrong..

The guy put a few mods into it including a cold air intake, he lowered it quite a bit, and also two exhausts and I think they are cat back exhausts, he may have also done something else with the suspension because it seems really stiff.

Well first thing is I hear some sort of rattling under the car sometimes when im driving and I have no idea what it could be

2nd, any crack or bump is pretty loud and it doesnt sound right and I do not know what it could be.

3rd, the guy told me that on humid or rainy a sensor fills up with water because of the cold air intake he installed and the engine light turns on, well it jst recently turned on and im not really sure what sensor it could be.

4th, today while i was driving i noticed that when i would release the brake the car would accelerate way to fast it was weird, it would accelerate to like 20mph and stay there, i decided to pull over and put the car in park, the rpms were going up and down, i would like to believe its because of the sensor filled with water or something, but again im not really sure.

and last but not least, my brake light on my dash turned on and it seems like its for no reason, it turns on after I press the break to put the car into reverse or drive, but my brake light in the back work perfectly.

If anyone could help me out that would greatly appreciated thank you very much!

 

I will match your points
1, Look for a loose heat shield on exhaust as they rust away at the bolts
2, Look for worn suspension components and bushings
3, Get the code from the computer and post
4, What is the RPM at idle in gear
5, Is usually air in the brake system or failed master cylinder or both

 

I think I can answer at least #2, I would say the springs are shot

 

Mine rattled when the sway bar links were bad.

 

Which brake light are you talking about? The one that turns on when the e-brake is pulled up, or the one that warns you that a brake light is out?