Weld will not weld at a steady speed, it will weld good for a minute then start sputtering like it not getting wire and will burn the wire into the tip

Have you stripped and cleaned out carburettor?
sounds like a blocked idle jet?

What doesnt speed up to weld? the feeder? is the wire burning back? are you getting any wire? this is gmaw / wire right? sounds like it may be running slow

Best guess is O2 sensor is reading too much unburned fue in the exhaust for some reason and leaning out the fuel flow to compensate. Runs when you throw more throttle at it but leans out as you try to hold steady speed. Should throw a code though.

I've had slot of experience with these migs. Usually when the arc sputters, it could mean 2 things, either the roller feed tension is too light, or the liner in the pistol lead is worn. It's the flex tube the wire travels through. If it's worn the wire will hang up or snag, causing the arc to sputter. If you tighten the roller tension, and the wire back-lashes, that's a sign to change the lead. First try adjusting the speed of the wire accordingly to the heat.

can you adjust your voltage settings? you may be welding on material that is thicker than what your machine is designed for. your ground clamp may be loose or dirty.
it should sound more like bacon frying than popcorn.

Try moving the tip closer to your work and try turning your wire speed down
Most people want to crank up the wire speed when it spits and sputters
Turn it down
See if this helps

you should run power between 160-180 to get a godd weld with out burning your work

Since it ran fine before you "fixed" it, go back over the things you changed. Put the old spark plugs back in it. Double check all spark plug wires and ignition connections. Put the bike in a dark area and run it at night, can you see any arcing anywhere?

I have the same welder. Worked well for 15 years until the drive bearing stopped spinning. I cleaned and oiled the bearing and it has been working like a coon on the farm since. Nice 120 volt welder....

First make sure your work area is out of the wind
Get some of the same thin metal to practice with.
Use the thinnest wire you can get. Start on the lowest
Volt setting and wire speed start welding and increase
Your wire speed till it sounds frying bacon and use
Stitch welds about ½ long wait a few seconds then lay down
The next weld start at where you left off that way the metal
Has time to cool some dial it in and practice.