My 95 Blazer chugs, spitters & sputters @ 2000 rpms or higher, anything lower, seems to run fine. Then, when you shut it off, It might not start for 5-10 minutes. This all started about 1 week ago. 6 months ago, it had similar problems. I replaced the fuel pump, sending unit, fuel filter, plugs, wires, cap & rotor. No fix. I gutted the cat. No fix. I then took it in to the shop and had the fuel pressure checked, He said it was great. While he had it, it would not act up. I then replaced the spider. It ran fine till a week ago. It gets about 13 mpg befor and after all of the above, should it get better mpg ? I am scared to drive it, for fear of having to walk home. The service engine light, nor any other light is not on and never was. Also, not sure if this is related, but the battery/volt guage needle bounces when I turn the blinkers on. This has been happening since I got the vehicle. I never have had a charging problem, though. Any help would be greatly appreciated.

 

Try pulling the upstream O2 sensor (ahead of the catalytic converter). Completely remove it from the vehicle. Drive it like that (it'll be loud). See if it revs past 2k with that out. If it does, then you have a plugged catalytic converter.

 

Thanks for the reply, but I gutted the cat. 60 months ago. Any other ideas ?