Severe Stumble Intermittingly on my 90

[moesvette]

Ok, so I tried to pull codes last night (wire to pin K, and grounded to frame). I got nothing....no 12 flashes, nothing. I have never tried to pull codes before, so could be my inexperience, but I tried multiple times, even grounding to negative term of battery. Any suggestions? I did not use a paper clip in the K pin location, simply stuffed the wire in, but was sure I made contact with the brass part of the pin. HOWEVER, interestingly enough I just happened to check the battery cable to positive side of battery and it was loose. How stupid I am if that is all that was wrong. Tightened and fired up for 20 minutes at different idle revs, and never missed a beat. Couldn't take a drive as weather was bad so that will be tonight. Also checked fuel pressure: Static 48 psi, and after starting engine 42, when revving, it jumped up to 50. Thank you Shrade for the suggestion. Any ideas on how to figure out if I can pull codes?