I have a 98 blazer. I can drive it for like 5 or 10 minutes, but afterwards if i let the rpms go down, the car will die

If the catalytic converter was plugged to the point where it was causing a rough idle, the vehicle would have 0 power and the engine wouldn't rev past 2000rpm in gear. Do not poke a hole in the fuel filter. Its a $7 part and removing one side of the line gets you half way to full removal. The filter also prevents contaminates from entering the engine and fuel injectors. Contaminates clog injectors and can also make them stick open. Contaminates can also put micro scratches in the cylinder walls causing improper lubrication. Vacuum lines are a possibility. Low fuel pressure is a possibility and the need for a tune up is a possibility. Low fuel pressure gets worse with higher rpms. Vacuum leak symptoms disappear at higher rpms. The need for a tuneup tend to idle crappy, sometimes allowing a smooth cruise and runs crappy under a hard acceleration. The fuel pressure and vacuum will always be the way I described but a tune up can look like either, neither, or both. There are plenty of other possibilities but these three are usually where a mechanic starts because they are the easiest and most common.

i have owned 3 of these trucks and the only thing that will cause this if if there is a gap somewhere in the air inlet ducting these trucks wont stay running if its sucking in to much air