i have a 2003 chevy 2500hd and is havin a bit of a problem. I will start my truck no codes at all. it will idle fine and all that. Once i put it into gear it studders and has no power it crawls even at full throttle. Then it will through a p0300 code for a little bit after i leave off the gas it goes away. Any one have an idea what the problem could be. also the cats are stock with 97,000 i dont know if it is tranny or cats or maybe sumtin else i dunno any ideas

 

0300 is engine misfire.

Good source material for troubleshooting: Engine misfire detected.

Related tech info:

These DTC’s will
determine if a random or a
cylinder specific misfire is
occurring by monitoring
crankshaft velocity.



Deceleration index
Vs
Engine speed
Vs
Load and Camshaft Position
Emission Failure Threshold = 1.67%
Catalyst Damage Threshold = 5% to
14.17% depending on engine speed
and engine load


Engine run time > 2 crankshaft revolutions.
DTCs not active for VSS, CKP, TP, MAP, ECT,
MAF, and IAT sensors.
No engine protection faults.
P0315 (Crankshaft Position System Variation Not
Learned) not active or engine speed < 1000 RPM.
Fuel cutoff not active.
Power management is not active.
Brake torque management not active.
Fuel level > 10% (disablement ends 500 after a
low fuel level condition ceases, and fuel disable
does not occur with a fuel sensor DTC).
-7C < ECT < 130oC.
 If ECT at startup < -7C, then disable until ECT >
21C.
400 RPM < Engine speed < 5200 RPM.
11 volts < System voltage < 18 volts.
+ Throttle position delta < 15% per 100 ms.
 - Throttle position delta < 15% per 100 ms.
Abnormal engine speed is not present.
ABS rough road not detected.
ABS is not active.
Not an abusive engine speed condition. Abusive
engine speed = 6100 RPM. Abusive engine
speed delay = 1250 cycles
Positive and zero torque (except the CARB
approved 3000 rpm to redline triangle). Positive
and zero torque is detected when both is true: 1)
engine load > zero torque cal (cal a function of
engine speed and temperature), and 2) TPS > 1
or VSS < 30.
Detectable engine speed and engine load region.
Misfire Diag is not requesting to disable TCC
when transmission is in hot mode.
Crankshaft Ring Filter inactive (after a low level
misfire, another misfire may not be detectable
until crankshaft ringing ceases)