Stalling issue

[Emcoord]

I’ve got 97 gmc serria w 5.0 v8 Ext can 4x4 the truck has 150k on it and the head gasket started leaking internally. So had the head gaskets replaced at the local shop. Got the truck back and noticed a hard start when cold and poor throttle response and a engine code. Took it back to the mechanic and he put a computer on the truck. No more codes or misses but the throttle response is horrible and it will stall out by patting the accelerator, still starts hard cold. I just put plugs and distributor cap on 10k ago. Pretty sure it’s not the fuel filter. So the mass air flow? Dirty throttle body assembly? TPS? Throttle body gasket not sealing right from the head replacement? I’m really not sure. I don’t want to take it back to the mechanic again. Any opinions or tips I’ll appreciate and I’m new here so thank you and hello.

 

[evilunclegrimace]

Is the Cam position offset correct? He had the distributor out and if he did not set the CPO correctly it may cause hard starting and poor throttle response

 

[Emcoord]

Is the Cam position offset correct? He had the distributor out and if he did not set the CPO correctly it may cause hard starting and poor throttle response

I did have the timing checked last week and it’s timed correctly. Is this the same thing as the CPO being set correctly? I’m not familiar with a CPO

 

[evilunclegrimace]

I did have the timing checked last week and it’s timed correctly. Is this the same thing as the CPO being set correctly? I’m not familiar with a CPO

Checking the timing is not a good indicator as the computer controls the timing. The camshaft position sensor offset must be set correctly for the computer to correctly adjust the timing,

TEST PROCEDURE
The ignition timing cannot be adjusted. The distributor may need adjusting to prevent crossfire. To insure proper alignment of the distributor, perform the following:



With the ignition OFF, install a scan tool to the DLC.
Start the engine and bring to normal operating temperature. IMPORTANT: Cam Retard Offset reading will not be accurate below 1000 RPM.
Increase engine speed to 1000 RPM.
Monitor the Cam Retard Offset.
If the Cam Retard indicates a value of 0°+/-2°, the distributor is properly adjusted.
If the Cam Retard does not indicate 0°+/-2°, the distributor must be adjusted.
ADJUSTING PROCEDURE


With the engine OFF, slightly loosen the distributor hold down bolt. IMPORTANT: Cam Retard Offset reading will not be accurate below 1000 RPM.
Start the engine and raise engine speed to 1000 RPM.
Using a scan tool monitor Cam Retard Offset.
Rotate the distributor as follows:
4.1. To compensate for a negative reading, rotate the distributor in the counterclockwise direction.
4.2. To compensate for a positive reading, rotate the distributor in the clockwise direction.

Repeat step 4 until 0°+/-2°, is obtained.
Turn the ignition OFF.
Tighten the distributor hold-down bolt to 3 Nm (25 lb. ft.).
Start the engine, raise engine speed to 1000 RPM and recheck Camshaft Retard Offset.

 

[east302]

I’ve got 97 gmc serria w 5.0 v8 Ext can 4x4 the truck has 150k on it and the head gasket started leaking internally. So had the head gaskets replaced at the local shop. Got the truck back and noticed a hard start when cold and poor throttle response and a engine code. Took it back to the mechanic and he put a computer on the truck. No more codes or misses but the throttle response is horrible and it will stall out by patting the accelerator, still starts hard cold. I just put plugs and distributor cap on 10k ago. Pretty sure it’s not the fuel filter. So the mass air flow? Dirty throttle body assembly? TPS? Throttle body gasket not sealing right from the head replacement? I’m really not sure. I don’t want to take it back to the mechanic again. Any opinions or tips I’ll appreciate and I’m new here so thank you and hello.

What was the code...and did they just clear it or did they repair something in that second visit?

 

[Emcoord]

What was the code...and did they just clear it or did they repair something in that second visit?

they cleared the code

 

[Emcoord]

they cleared the code

the mechanic said he computer was bad and replaced it on the second visit.