240sx not running right and i need some help

[randrade]

First off im new to the 240 world and have no idea whats going on with my car. I just recently bought a 95 240sx that has a red top sr20det in it. For about the first 2 or 3 days the car ran perfectly fine and out of nowhere it started to basically bog out whenever I started to get on it. In first gear it starts to bog around 6000 rpms. 2nd gear around 5000 rpms in 3rd around 4500 rpms and in 4th around 3500 rpms. Ive changed spark plugs and it went away in first gear for about 2 days but returned. Ive been thinking maybe its the maf sensor and I just ordered a new one a few days still waiting for that to come in and try that out..... Any ideas on what it might be?