low end power lose

working on a 05 3000gt. On low end acceleration it misses but not a constant miss. Has after market exhaust and air cleaner. Recently had a tune up?????????????????????????????????Any help would be appreciated. Thanks

Could be:
Exhaust leak
Bad O2 sensor
bad cat
Bad spark plugs/wires

Do you get an check engine light?

I get "vehicle is not responding" on my code reader but it might not be working correctly. Any more info would be appreciated and I will start with your helpfull advice thankyou. I am just trying to help out a fellow hot rodder to save some cash. also when the car is cruising with no load it runs fine. Sorry I didnt mention that at first. When you hammer it it spits and sputters untill you get the load off then it smooths out and runs fine. Thanks again

+1 on the bad spark plugs.

a) '05 3000gt???? I'm guessing that was a typo lol. What year is it? Because if you meant 95, then it's a hybrid ecu and an obdII scanner wont work on it, you'll have to retrieve the codes manually. If it is in fact older than a 96, and you don't know how to manually pull the codes, let us know, and we'll get into that. Also, there isn't a point, unless there is in fact a check engine light on.

b) plugs never hurt to change. Get some cheap NGK coppers. These cars, like many, hate Bosch plugs so avoid those. The coppers will cost a buck a piece and can be swapped in a half hour to an hour.

c) how many miles on the car, and how recently was this recent tuneup, and what all was involved in the tuneup. The more info you give us, the better we can help.

yes that was a typo and thanks for all the advice. I am an old school hotrodder so some of this stuff is strange to me but horse power is horse power no matter how its made. The NGK plugs and plug wires did the trick. He paid $500.00 for champion spark plugs from some shop and thats all they did. Pretty sad. Its screams now and again thanks for all the help.