Feel like someone is pushing me from the back

[ZO6 WA BAS]

when i am driving my c6 zo6 at a speed between 20 to 60 m/h, the car feel like someone is pushing me from the back(like hesetating) and then back-off!! This does not affect my car performance at high speed, i have changed the spark plugs and the alternator with no success.
This problem started when the car run out of fuel at the dealer garage and when they filled the car with the fuel and start the car, i saw a large black smoke coming out from the exhaust!! Then stoped and then the hesetating started.
The dealer doesn't have any idea, they said i have to check my new tunning.
I had 2 programmers checked my ecu tunning and there were nothing wrong.

Please advice
thank you

[c4c5specialist]

HI there,
First, you will need to tell us your mileage.
next, your modifications could change things like spark plug performance.
Your ignition wires could be shorting against the headers if you have them.
Check that first.

Then, make sure your mass air flow is correctly connected to the engine.

Allthebest, c4c5

[ZO6 WA BAS]

THANK YOU "c4c5specialist" FOR YOU QUICK REPLY.
THE CAR DID 8000 KM THEN THE ENGINE DAMAGED AND I HAVE CHANGED IT WITH A COMPLETE BRAND NEW ENGINE AT THE GM DEALER, THE CAR NOW DID 11000 KM.
I HAVE JUST NOW CHANGED THE ORIGINAL SPARK PLUGS TO TR6 AND CHANGED THE WIRES TO 12MM GOOD QUALITY ONES AND DRESSED THEM WITH GOOD INSULATORS. ALSO I CHANGED THE FAN COMPLETE UNIT BECAUSE IT WAS NOT TURNING AND FOUND THAT THE CONNECTER TO THE FAN UNIT WAS BURNED!!(I HAVE BEEN TOLD IT WAS THE DEALE GARAGE NOT INSERTED THE CONNECTERS CORRECTLY!!) AND THE FAN WAS HARDLY TURNING EVEN WITH THE DIRECT LINES!!
ALL THIS WORK WAS DONE IN MY HOUSE AS I DON'T TRUST OUR DEALER GARAGE ANY MORE.
I JUST TRIED THE CAR AND THE FAN RUNS AT THE START AND ONLY STOP WHEN I SWITCH THE CAR OFF!! THE WATER TEMP. GOES TO 84 DEG.CENT. WITH THE AC ON. THIS IS VERY GOOD FOR ME AT THIS TIME OF THE YEAR HERE. BY THE WAY, THE FAN WAS NOT PROGRAMMED AFTER THE MODS.TO DO THAT!!.
REGARDING THE MAIN PROBLEM OF HESITATING IT WAS ALMOST GONE BUT I DON'T KNOW IF IT WAS BETTER DUE TO:
1-CHANGE TO COOLER PLUGS.OR
2-CHANG TO THICKER WIRES.OR
3-CHANGING THE HARDLY WORKING FAN UNIT AND BURNED CONNECTOR TO NEW ONES.

I DON'T KNOW WHAT YOU MEAN ABOUT THE MASS AIR FLOW NOT CONNECTED TO THE ENGINE CORRECTLY!! WHERE IS IT?

THANK YOU

[ZO6 WA BAS]

hi there,
i would like to update you with my car foundings now.
The hesetating came back and it is the same as before, if i am driving say 100 km/h and then just moved my foot from the baddel very little then i feel like the car going back and front(not much but you can feel it hapenning).

Regarding the fan, my friend think the problem is with the fan moduler, not working proberly.

What do you think?

[c4c5specialist]

HI there
Your trying to address 2 different concerns.

If your fan module is bad, it will set diagnostic codes and also, the engine tune could also create the issue, as if you have the on time of the fan module at over 90%, you can destroy the electrical connections as happened before.

As for the misfire, you will need to investigate further, as I am unaware of the type of fuel you are running where you are.

Allthebest, c4c5

[ZO6 WA BAS]

Thank you
my fuel is a 97 octane unleded

[2006C6KELLER1]

Pour some "water eliminator" in the gas tank, there just might be some water in the gas tanks. Good luck. I've been there before. You have to be careful of fuel sources, think back and you might figure it out where you have been buying gas, dealer possible?