1995 Nissan Maxima

Engine Performance problem
1995 Nissan Maxima 6 cyl Front Wheel Drive Manual

My 1995 maxima Check Engine lite has been on for 6 months with no apparent problems or power loss. Recent computer analysis indicates mass air flow sensor and oxygen sensor problem codes. Since then I let my engine over heat.

1. Is there another way, besides looking for coolant in my motor oil, to find if I blew the gasket or cracked the block?
2. Could a bad MAF cause such erratic infrequent sputtering as discussed below?

My radiator is cracked and caused overheating when I failed to watch water level and the engine sputtered badly and lost power until I added water. However, approximately 2 weeks later, with a full radiator, my auto started erratic, power loss, sputtering “fits" when starting from idle at stop signs and lights, but, oddly, this occurs only roughly once in 25 such starts.
I cleaned the MAF hot wire and she ran great, but immediately regressed to her “fits" now roughly once per 35 starts. One mechanic feels the MAF wire is bad.
Nissan ran their computer diagnosis, found the same problem codes with Oxygen and MAF sensors. Nissan feels the culprit is the MAF.
But first, before I invest $950 for sensors, I want to check if my engine block or gasket is cracked from the overheating. Nissan looked for coolant in my engine oil but said they couldn’t determine any leakage because I had recently changed my oil. I have fearfully driven this car about 90 miles merely to see if coolant will leak into the motor oil.