99 Blazer 4.3 4WD Rough idle weak choppy accelaration

[travis2822]

Truck has been running fine until today. I drove about 10 miles on the highway. I got off onto the ramp into the intersection. I felt the truck start to stumble a bit. Put it in nuetral and i could feel a rough idle. The light turned green and I put it into drive and had very little accelaration. When I get to about 20mph acceleration is a little bit better but still rough.
There is also a rotten egg smell that started coming from my truck.

I also hear a rattle located in the middle where the rear drive shaft connects. Rattle goes away upon accelaration.

Thanks for help.

Tune up was this summer.
Below are the codes Autozone pulled for me.
P0300
P0452
P0142
P0453

No light until today. Blinks while accelerating and is solid at idle.

Thanks again.

[viggy58]

start with checking your fuel pressure...
make sure the engine is nice and warm when you do.

any check engine light?
when was the last time you had a tune up?

[travis2822]

Tune up this past summer.

I'll check fuel pressure although pump was also replaced this past summer.

Check Engine light was not on until today and it started blinking.

[travis2822]

The rattling noise is coming from the catalytic convertor. Does that mean it is bad? Could that cause the code P0300 and performance issues?

[old_master]

P0300 is usually caused by secondary ignition failures: Distributor cap, rotor, plug wires, and spark plugs. When the SES blinks on acelleration it means the engine is misfiring. Misfire can cause a raw fuel odor. These engines can be very fussy when it comes to secondary ignition parts. Aftermarket parts usually cause more problems than they're worth, stick with AC Delco parts. A rattling converter can cause a lack of power. If the insides are loose, it needs to be replaced. Fuel pressure is critical on the 4.3L and again, aftermarket parts don't make the grade. Ignition ON, engine OFF, fuel pump running: pressure must be 60psi to 66psi and must remain above 55psi for 3 to 5 minutes after the pump shuts off.

When it comes to DTC's, (diagnostic trouble codes) always diagnose and repair the first DTC that is retrieved, clear the codes from memory, and perform a drive cycle, http://www.obdii.com/drivecycle.html If the SES light comes on during or after the drive cycle is completed, repeat the steps above until the SES light no longer comes on. Any DTC's that appear after the first one, can be caused by the first one, that's why they need to be diagnosed and repaired in order.

[travis2822]

Thanks for the help. I changed the plugs, wires, distributor cap, and rotor with AC Delco parts and my truck is running like a champ again.