'95 cadillac eldorado driving and went to pass a car. The engine would rev up to 4000 rpm and car would slowly go. check engine light came on. I parked the car and turned it off. when i restarted the car the system check was ok and check engine light turned off. - what would cause this?

you are trying to go higher then the rev limiter its normal operation

Neutral or Drive N rev limiter to prevent engine damage from no load over acceleration. D: many things could be at fault. Has your fuel filter been changed in the last 30,000miles. What about a tune up? Is your CEL(Check Engine Light) on? If so have a parts store check for codes, some do it for free. Then get back to us and we can go from there.

if your looking for a bypass belt to go without ac for a 95 cadillac eldorado this is the one you need CarQuest (No. K060739) i just went and got one and it fit like a glove starts everytime now

Hi Tom your vehicle is equipped with a Rev limiter it will not allow you to rev the engine above 4000 with the trans in park; as for the first problem you may have one of two things, one of the spark plugs or spark plug wires is bad or you have a flat spot on the throttle positioning sensor in which case have be replaced. Good luck?

The vehicle has a rev limiter. Will it rev over 3500 when you drive it? If no, then I would guess that the exhaust might be partially restricted. But the engine computer won't allow you to free rev the engine that high in park and neutral.

Check gearbox oil

The 300M is equiped with a rev-limiter. The technology is designed to protect the engine. It keeps you from blowing it up when it has no load on it...If it is driving and shifting ok, and you have no check engine light on...there is nothing wrong.
Why would want to rev the engine past 4000 rpm in neutral anyway? Max torque comes in around 3950 RPM...
If you keep reving it up in neutral you might throw the computer in to LIMP mode, then you wont go no where.
Hope this answers your question...

CSP, It sounds like you have a vacuum leak that is causing the IAC ( idle air control ) motor to move in and out trying to control the idle. Check all vacuum hoses on the engine for disconnect, cracked or damaged. If the hoses crack when you bend them, they need to be replaced.
Let me know what you find and we can go from there.
Regards,

Hi    try this  switch on ignition without starting depress gas pedal fully and hold down for a second or    two then start the car and lift up your foot slowly when it fires. sometimes this will reset ECU    let me know if this works

I have a 1994 Cadillac Eldorado and every time i start it the car has rough Idle and the Idle fluctuate's. I also can feel it in the gas pedal when the car is doing this I tried replacing the throttle body sensor but it still does it I also was told it was the Idle error sensor. So instead of spending the unecessary money again I thought I would go online and see if anyone could help me with this problem.