I got a 98 blazer with 66000 on it, bought it with 46200 for 500 bucks replaced the alternator that was wrong with it and everything with the breaks except the master cylinder and the abs module, so break lines, rotors, calipers, pads and rubber break lines all the way around. I had it for about a year, I drive a lot for work, a lot of traveling due to the major increase in mileage,About 4 months ago someone hit my rear and only damaged done was bent the exhaust downward. After driving a few months I started hearing a whistling noise, did some looking around found that the flange that connects my back half of the exhaust to the front part cat manifold ect. I tried and tried to get the bolts out and replace them but ended up doing a quick fix of using vicegrips to clamp my exhaust together!! Reason why is that was loosing acceleration, I was figure due to back pressure or the leak causing the ECM to run the engine rich causing g a flooding engine, it actually fixed the problem, but it started doing it again with loss of power and acceleration, I dont have a gas cap, do you think with the evap not pressurized right can cause this issue as well, of do I really just need to get both fix and see if fixed the issue?

 

You should install a gas cap for at least safety reasons. It might also solve your problem too.

 

I pulled a map sensor code took it off cleaned it and got to check engine code to clear on it's own, pulling no evap codes whatsoever!! Still no acceleration and power and the engine acts like it wants to stall out