My car zen vx 1999 does not run smoothly especially in sudden pickup as if it does not enough petrol. please suggest

run the fault codes
check for problem position sensor or wiring
check for ignition control module problem

most shops will charge you a minimal amount to put it on a diagnostic test. If you have done the work yourself I would suggest pulling the test plug on your catalytic converter and if that increases power it needs to be replaced. good luck!

run fault codes and look for a failing O2 sensor. Check for cat converter failure and blockage.

check if it is a petrol engine if you have any electrical problem like coil or crank sensor or cam sensor or idle speed control sensor

I'm not sure of this, but my friend experienced similar situation.
He had a Kia Pride used for Taxi cab. He have replaced damaged parts, replaced freon for his aircon and overhauled the engine. The cab really runs smoothly and in good condition.
But from time to time, the engine stops. Just like you, everything is normal, but stops unexpectedly. We even have it checked from my friend mechanic and said that everything is normal. He gave up the car and he loosed around PhP50,000.00 at that time (enough to pay rent for a year. He later found out that the car runs OK again...
THE NEW OWNER HAVE THE WIRING AND ELECTRICAL CIRCUITS RENEWED!
And a car owner claims for the same problem, I said its ELECTRICAL CIRCUITS, it should be replaced. When she have it fixed, the mechanic have her car's wiring replaced. And it runs smoothly again.
Please try...

clutch could be worn out ?
how many miles since it was replaced ?

Hi and welcome to FixYa!

Sluggish runs are caused by a worn out torque converter. I strongly suggest that you have it replaced, after the replacement a smooth drive and shifting will be noticeable.

Hope this helps and thank you for using FixYa! Have a good one!

spray some carberator cleaner (GUMOUT) directly into the cavity while running until it runs smoothly

time to replace bank 1 and bank 2 o2 sensors.

are there any fuses to check why my car wont start on gas...?