Someone was having fun with you I think, You should have a scan tool hooked up , check the map sensor , O2 sensors . coolant temp. fuel pressure .I don't know what year your S-10 is but , this will work for any year !
1999 Chevrolet S10 Pickup - 2WD ' Blazer, Bravada, Envoy, Jimmy, S10 Pickup, Sonoma (VIN S/T) Service Manual ' Engine ' Engine Controls - 2.2L ' Diagnostic Information and Procedures ' Document ID: 320398
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Surges/Chuggles
Surges/Chuggles Checks
Action

DEFINITION: Engine power variation under steady throttle or cruise. Feels like the vehicle speeds up and slows down with no change in the accelerator pedal.

Preliminary
• Refer to the Powertrain On Board Diagnostic (OBD) System Check .
• Refer to Symptoms .
• Search for service bulletins.
• Be sure the driver understands the transmission torque converter clutch, and the A/C compressor operation as explained in the owners manual. Inform the customer how the TCC and the A/C clutch operates.
• Check the PCM grounds for being clean, tight and in their proper location.

Sensor/System
• Check the Oxygen sensor (O2S 1) and the Heated Oxygen Sensor (HO2S 2). The O2S 1 and HO2S 2 should respond quickly to different throttle positions. If not, check the O2S 1 and the HO2S 2 for silicon or other contaminants from fuel or the use of improper RTV sealant. The sensors may have a white powdery coating. Silicon contamination causes a high but false O2S 1 and HO2S 2 signal voltage (rich exhaust indication). The PCM will reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Refer to Oxygen sensor and the Heated Oxygen Sensor in the Information Sensors/Switches Description .
• Check for proper operation of the MAP sensor.
• Check for proper operation of the TP sensor.
• Check for proper operation of the ECT sensor.

Fuel System
• Check the fuel pressure. Refer to Fuel System Diagnosis .
• Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
• Check the fuel filter for being plugged or restricted.
• Ensure each injector harness is connected to the correct injector/cylinder. Refer to Engine Controls Schematics .
• Check items which can cause an engine to run rich (long term fuel trim is significantly in the negative range). Refer to Diagnostic Aids for DTC P0172 Fuel Trim System Rich .
• Check items that can cause an engine to run lean (long term fuel trim is significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 Fuel Trim System Lean .

Ignition System
• Check for proper ignition voltage output with spark tester J 26792 or equivalent.
• Check the spark plugs for the following conditions:
- Check for wet or fuel fouled spark plugs.
- Check for cracks on the spark plugs.
- Check for wear.
- Check for improper spark plug gap.
- Check for burned electrodes or heavy deposits.
• If the spark plugs are fuel or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
• Check the Ignition Control Module (ICM) for proper ground connection.
• Check the ignition coils for cracks or carbon tracking.
• Check the spark plug wires forproper resistance and condition.

Additional Checks
• Check for proper operation of the TCC. Refer to Torque Converter Diagnosis in Automatic Transmission 4L60-E.
• Check the exhaust system for a possible restriction:
- Inspect the exhaust system for damaged or for possible collapsed pipes.
- Inspect the muffler for heat distress or for possible internal failure.
- Check for possible plugged three-way catalytic converter. Refer to Restricted Exhaust System Check or Exhaust System Inspection in Engine Exhaust.
• Check the vacuum lines for kinks or leaks.
• Check the generator output voltage. Repair the generator if the output voltage is less than 11 volts or more than 16 volts.
• If all procedures have been completed and no malfunctions have not been found, review and inspect the following items:
- Visually and physically inspect all electrical connections within the suspected circuit and/or systems.
- Check scan tool data.
This is information for the professional TEAHNICIAN That has a capably scan tool ! If your not familiar with OBD2 an electronic fuel injection systems I suggest very strongly that you take it to a certified technician !
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