GMC Repair: 97 GMC Sierra 5.7 hesitaion, throttle position sensor, egr solenoid

Question
97 GMC P/U with 5.7 (2WD) 150K miles.  hesitates when I depress accelerator then catches.  It usually occurs for mild depressions like accelerating for on ramps, up a hill etc.  Fuel filter, plugs, wires, distrib cap/rotor are new.  Just did an injector cleaning.  Problem was there before I did all this.  Seems to happen in warmer temps.  First noticed it going down highway at 65 when I accelerated to change lanes.  Has happened at slower speeds since. Fuel pump turns on at start but haven't put a guage on it. Any ideas?

Answer
Try cleaning the throttle body and the idle air by-pass hole just in front of the throttle plate inside of the throttle body with carb cleaner as a blackish residue tends to buildup in these areas.

Possible fault in the EGR solenoid providing to MUCH vacuum to EGR valve.

Possible slight fault in the TPS. (throttle Position sensor).

Weak fuel pump pressure/volume.

May or may NOT illuminate the check engine light on any of the above.


These are the most common.


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