The back of the car is very low and the car bounces when i drive over the bumps in the street it is a gmc envoy 2002 sle

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Could be the exhaust system hitting on something when the suspension moves. Inspect under the car and look for shiny spots that are making contact.

There is usually an idle solenoid on the throttle body that is designed to bump up the idle when the A/C is switched on, this could be bad, or out of adjustment.

2002 Envoy sle 4.2 L straight 6. Random misfire(PO300). After erasing codes for several days, I finally took my car on the highway and ran it at high speed(70+) for about 4 to 5 miles. Check engine light came on as before but this time it gave me(PO305). Random misfire cylinder 5. So I switched coil 5 with coil 2. Went back out on the highway and repeated as before. This time it gave me(PO302). This was telling me I had a bad coil. Replacing one coil pack solved the problem. The professionals told me low fuel pressure would not give me random misfire, but rather a O2 code because the engine is running lean. Thank you------------------------------------ thank you very much.

Gap should be around 0.043"
Also, make sure to use only AC Delco 43-103 plugs, these are the OEM plugs and work best in these engines.

If it bounces over bumps than it is you're shocks, consider replacing youre springs as well.

On he very top of your engine, there will be six coil pack, they all look the same, from front to rear of engine, remove 10mm bolt, disconnect elec. harness, pull coil pack out, spark plug will be in there, do one at a time, this is the spark plug gap .044"

could be sensor,floater, or gusge itself

low brake fluid

ENGINE LIGHT