Need HELP/Advice 96 Olds 88 Ls problems

I have a 96 Olds 88 Ls that was given to me in October of last year. I took it to a shop locally and they replaced the radiator and the 4 celinoids(?) in the transmission and told me it was in great condition. About a month later the heater fan blower began to run after the car was turned off and I removed the heater fuse in order to prevent the battery from going dead, and the heater blower fan relay hasn't been replaced, so the fuse is still out. In December the car began stuttering, dying at stops and having trouble excelerating and staying the same speed up inclines on the highway. Then I began to smell gas and slight burning odors. In the past month the catilitic converter has been bypassed and the fuel filter, egr valve, spark plugs and wires, oxygen sensor (rear), and return fuel line have been replaced. It is still stuttering (as badly as before), struggling to acelerate, there's still a slight gas odor and it is now ocassionally making a squealing noise. Can you please help me figure out what to do with this car? I desperately
need it.

If this is an auto temp system, most likely the blower control module....

How was the cat bypassed?

Codes?

they took the entire thing off the car, cut it below the cat., said it was fried, knocked alot of coal looking stuff out of it, welded it all back together and put it back on the car.

How would I find out if it is an auto temp system? I assume you are referring to the heat/ac...?

oh, codes read: cat., fuel filter, egr valve, spark plugs and wires, oxygen sensor

Yes I am talking about the HVAC system.....manual systems have a resistor block.....auto systems, have a blower module....usually when the blower motor doesn't shut off with key in the off position, it's the blower module.....one thing to note......sometimes it's a bad blower motor(that spikes), that can cause the problem with the module.....so, you may replace the module, and the same thing may happen if you don't replace the blower motor too....it's rare, but it happens...

What you did to the cat is illegal, and will set a code P0420, because there is no catalyst in the converter...that rear O2 sensor is doing nothing with no catalyst in the cat....

Sounds like you have a misfire...a code P0300 is not being set?

Check the vac line to the fuel pressure regulator to see if there is fuel in the line....

If the car idles rough, or hard to start, start car with the MAF disconnected, to see if there is a difference.....

If you have a misfire, check coil output with a spark tester....