My 97 360 started up at a really low rpm compared to usual (1 tick above 0) and almost cut off then went to normal idle. Drove fine but coming to stops the rpms drop unusually low again. It did die once while slowing down and started right back up like nothing happend. Every time I start the truck so far it has really low rpms each time then goes to normal idle. Any ideas on what could cause this? We did gut the cat a week ago but ran great up until now have no idea if it's related.

 

I have a extra pcm and switched it out so far been running normal again. Test drove and rpms stay normal driving and stopping again. Hopefully that fixed the problem. Noticed little bits of sand in old pcm connection points probably didn't help.

 

May wanna give the throttle body a good cleaning as well....