99 yukon starting problems/missing

Had starting problems-turn key it would turn over then on second or third try it would start and drive fine. Took it to mechanic. Computer showed bad o2 sensor. We replaced number one but not the others. We replaced the coolant sensor and I think the fuel control module part number TP58 at NAPA. Drove it home and great. 4 hours later- turn key nothing, turn it again and it would start. Then it missed when driving and giving it gas. So back to the mechanic and the computer showed no problems. Mechanic said maybe computer was adjusting for new sensors.

Ok, now drove home 700 miles and no problems. Next morning- turn key and nothing, second attempt started ran great. Drove to work. After 10 hours of sitting- turned key nothing, turned again and it started. Now the car was cold and missed all the way home.

Thoughts- had fuel pump replaced 7,000 miles ago and have not re-checked fuel pressure. Could the fuel pump be bad?
Did not replace all of the O2 sensors?
Have not had tune up for 30,000 miles?
Starter needs replaced as the mini starter is loose and very infrequently have to wiggle the wire to get it started?
Battery is newer but has some corrosion?

Can drive it but do not want to get stuck. Does anyone have a good place to start?

Thanks

What does turn key " nothing" mean? Crank but will not fire or the starter will not engage?

At first before the new modules it would crank and start on third try or so. Now occassionally when I turn the key the first time it will do nothing. Then it will turn over and start.

Mkay dmac72, don't like the part about wiggling the wire to get the starter to do it's thing. You know that it needs replacing and if it's the original on a '99 I'd say just go ahead and change it out. Prices aren't that bad on starters nowadays and you can get a rebuilt one really cheap or go with a brand new one if she's a keeper. Let us know how it turns out. Now as for the missing, I'd say double check your plugs and wires, since you did mention it's been awhile since the last tune up.