O2 Sensor?

[nn2004]

I'm sure you guys remember my many complaints about my truck running very poorly occassionally after exceeding 35 MPH. This week, I disconnected the O2 sensor and have been driving it like that since. It has only began to stumle once or twice since I did that. After about 10 mins and after I start climbing the hills here up in Silver City, NM , the SES light came on like it should. I have already replaced the Coolant Temperature Switch, which in turn made this thing not ever want to start in the morning at all (the other problem). It tends to be very cold blooded. I thought EFI systems didnt need to be warmed up, but mine does or it'll die. Should I go ahead and throw in an O2 sensor? They're kind of expensive, but I do want it to run right I suppose. Is it impossible to remove without the special socket that the Big 3 suggest buying? Thanks anyone.

Nathan