Huge triangle being followed by an F-16 in the california desert..

I was driving east on Interstate 8 just west of el centro california.,  I was a truck driver back then and my partner was in the bunk sleeping.,I,m trying to get to yuma, Arizona for our last pick up., before heading home to south carolina.,there was no traffic at all, just a boring drive with no one to talk to on the cb/it was a clear day,sunny and hot...something caught my eye in the distance, a long black line low in the sky with a tiny dot in back of it...it seemed to be just south of the interstate coming n nw right towards me.. As it got closer it got bigger and I estamated it to be several hundred feet long and it was only up at about 400 ft in altitude...I now can see what was behind it..A F-16 FIGHTER JET...It crossed over the hywy right in front of me and banked left..that's when I saw the whole shape of it//A Triangle, BLACK - NO LIGHTS- NO MARKINGS- It had a matte finish to it..I est. the speed to be around 600 mph//Too slow to be called a chase,.The F-16 just stayed on the left rear corner of it like it was filming it or something.,I found that to be strange...this could have been an early type BBD BLACK PROJECT type of craft...any way,it banked left and was gone from my site,It headed west north west..I didn't say anything to my partner, All I thought was how can something that big ever get off the ground.. 250 to 300 ft per side? what do you think?