Engine hesitates no codes

My engine started to hesitate really bad a few days ago. I thought I ran out of gas but that was not the case. My mechanic drove with me while the engine hestitaded and no computer codes. I sometimes feel like the car is stalling and have trouble getting it to run smooth. I unplugged the EGR connector and it runs great. My mechanic says that the computer is compensating for the unplugged egr and that is not really the problem. Any one have any ideas if its the egr or crank sensor??
Thanks

Welcome to AF. If the egr is is sticking open partially or the unit is carboned up this could give you the symptoms mentioned, as far as the mechanics comments, find another one. BTW always post the year and engine size.

Sorry, 1999 Pontiac Montana 3.4ltr

Thanks for the info, I had a feeling the egr was the problem.

After driving 100 miles with the egr unplugged, the engine started to stalland hesitate stall again, so I plugged it back in.. I drove it today, started to hesitate, then got worst. After about 15-20 miles, the check engine light came on and started to flash. now the code is comes up misfire.

I thought it might be the fuel pump starting to go bad. Pressure checked ok but the hesitation wss not happening during the pressure check.

Flashing lite is a serious enough misfire to damage the cat, bad plug, bad wire, bad coil, low fuel pressure, bad injector all possibilities here. What p0 code was it?

I believe it was "unrecognizable misfire"

just got off phone with my mechanic-- code 300. He said we have spark to all cylinders. only one doesnt vary when removing the plug wire, possible bad injector.
Thanks

Today, my mechanic used a brand new scanner and cylinder 5 is misfiring. He used a special sound detector and the injector selanoid is activating. So on Monday he is replacing the injector (clogged). Maybe this was my orginal problem and just got so bad that all it does is misfire now.

Today, my mechanic used a brand new scanner and cylinder 5 is misfiring. He used a special sound detector and the injector selanoid is activating. So on Monday he is replacing the injector (clogged). Maybe this was my orginal problem and just got so bad that all it does is misfire now.

Personally. I would perform an injector balance test to see what the condition of the other injectors are.
If the injectors have clogged director plates, cleaning will bring them back to a good working order.
If the filter on top of the injector is plugged, you have corrosion in the fuel system and will need some further repairs

Well, After a couple of days comunicating with Jasper Engine (2 yr old rebuilt engine), my mechanic removed the head and found that the cylinder #5 rocker arm was loose. He removed it and found the push rod had fallen out of place. He inspected the rod and found it ok, and re-assembled the head. He also found that the injector on the #5 cylinder was not closing, thus allowing fuel to enter the chamber continually.
Now my car runs like NEW. No more miss firing and hestitation.

Thanks for all your help.
Steve