I bought a 1999 Blazer, the previous owner had taken out the catalytic converter and welded on a straight pipe. Is this is what is causing my problem and if it is can it be fixed with out replacing the catalytic converter?

 

Does it happen just when you first start to accelerate? or everytime? I have same yr blazer and i would try to accelerate and the rpm wouldnt go up almost as it got stuck around 2 grand and would hesitate and the car wouldnt move. I replaced the mass air flow sensor, and it fixed my problem

 

Yea that sounds about right, Im gonna try that, everyone I go to tells me to replace the catalytic converter, but thats kind of pricey if its not gonna for sure fix the problem, some also suggested an O2 simulator, not quite sure how those work tho....

 

An O2 simulator will not help your problem. You cannot simulate the upstream sensors which are the only ones that deal with fuel management. A simulator can fool the PCM into not triggering an insufficient catalyst code, but this code has no impact on performance.

You can clean the MAF to see if that helps. Then go over the usuals in terms of checking for vacuum leaks, fuel pressure, etc.

When was the last time you performed a tune up?

 

Changed plugs, wires, and distributer cap about 3 months ago, I've only had the truck for 4.