Surging - where the engine speeds up and slows down - is caused by a lean fuel air mixture. The carburetors built after Sep 1997 were not adjustable or equipped with adjustable needle valves. Mixtures can be adjusted with replaceable jets located inside the carburetor. If the carburetor was rebuilt correctly, there are other things to check. If the fuel tank is mounted higher than the engine, remove the fuel line from the carburetor to see if fuel flows freely. Aim the fuel into a jar to see if there is dirt or water present. Flush any debris from the end of the fuel line before reattaching. Another check is to connect a vacuum gauge to the carburetor fuel fitting. This section of the carburetor is actually a vacuum operated fuel pump. Crank the engine to see if suction is present. If there is no suction, check the vacuum hose connection from the the crankcase. Sometimes the hose ends become cracked and vacuum is loss. Is the fuel tank in the rear of the tractor? Assuming the fuel pump has suction, attach the vacuum gauge to the end of the fuel hose to see if the fuel line is good. sometimes cracks form in the fuel line and air is drawn in. Look for cracks or loose clams on all fuel connections. Look for dirt and debris in the fuel tank. If the fuel lines are good, check the gaskets around the intake manifold to cylinder. A lean fuel air mixture could also be caused by worn valve guides - but is not likely on the opposed twin. Most likely there is still some dirt in the carburetor. If the float is the plastic style and the float has warped, the fuel level in the float bowl is too low. If the person who rebuilt the carburetor used fuel to wash the parts, the carburetor could still be varnished. A carburetor spray must be used to clean the internal parts.

Must of been lucky. Bought an MTD at Ace hardware (Ace Special Edition) with a 42" cut and 16hp Tecumseh. Aside from the normal problems of your MTD of that era IE having the grille mounts break off after a few years) it's been great, and it was only replaced as it was really starting to not work well on hills, and in the last year has been a case of "What's going to break next when I mow?". A key to remember is any NEW tractor in that range is going to be light duty. If you have more an acre to mow with it, a newer, higher end, used model is a probably a better option. You'll get a lot of life out of one though if you keep it well maintained. Take care of it and there is no reason why you should not get a good, usable life of about 10-12 years. one other thing to keep in mind; the chief complaints of many people on a mower it seems is the motor. That is the most important part of a mower besides the transmission on a Hydro equipped tractor. The engine is going to what will go wrong 9 time out of 10 on a mower, and is often going to be to blame for issues with cutting (due to lack of power) and reliability.

In addition to tomplums great advice I would also remove the gas tank and clean it out if you machine is a few years old. You maybe susprised whats laying at the bottom where the fuel pick up is. And if this machine is over 7 years old I would personnal change the fuel lines. That way I will not have to worry about a fuel contamination problem for quite awhile unless something unusual happens like fueling it with contaminated gas or letting it set for a long period of time with todays gas in it.

These chutes so seldomly fit like a glove, but you need to know that you have the right one. A 42" is different from a 46, 48, ETC. Installation tend to be easier with the deck lowered all the way. Some systems are different, but generally they need to be hooked out of harms way with a strap. Sometimes where they hook makes a difference. Excessive effort @ the PTO lever can be from debris or binding brake pivots on top the deck. The cables and the arm mechanism can be lubed. Sometimes unsnapping the cable from the holder below the foot pads and letting it simply rest on the top of the deck helps too.