Engine is sputtering when accelerating?

A few weeks back it started having difficulty starting occasionally. Sometimes It would crank but not turn over unless I gave out a little gas. It was not often enough that I felt it needed to be fixed yet. My son told me he thought it was the crank shaft sensor. Well two nights ago, driving home in a snow storm it started shuddering with acceleration any acceleration five mph or sixty mph. When you take your foot of the gas it stops. The idle is very low now and also vibrates in park. Could this be more symptoms of a bad crank shaft sensor or separate problems. Now, a few months back she shot a spark plug out of her head. Common problem I am told with the engine sizes for this year. We took the head to machine shop and had an insert put in. I think it might be a bad coil that got damaged when the spark plug shot out. Any help is very much appreciated.
Update**
Changed the crankshaft sensor and no change.

I have a 98 expedition, 5.4l. I'm having an issues with a light hesitation upon taking off from a stop or speeding up. If I'm on the highway and try to lightly speed up it kind of hesitates. It shifts fine and runs fine otherwise. The check engine light flashes at random at highway speeds but never when I have it sitting at AutoZone. I guess it's not storing the codes cause it always passes a scan. I'm thinking it could be one of the o2 sensors maybe? I just don't feel like paying the Ford dealer $100 to do a diagnostic if I don't have to! Help!

The vehicle ran fine up until yesterday. We've had it a total of 6 days and. Now. It. Seems tp have a vibration or shudder within the 40-55 mph range. It only does. It. When you accelerate between 40-55 mph. As soon as you let off the gas. It stops immeadiatly. Also got it within vibrate/shudder range and put it in neutral a.D. It stops then as well. The check engine light doesnt work I guess due to blowed bulb but I took to local autozone and its showing. Up that it has a misfire on #3. Mind you the vibration / shudder is quite noticable. As it sort of feels like you are rining over the bumps. They put in the road to slow you down. Checked the wheel bearings and they have no play movement. Checked the ujoints, they seem fine as well. We traded for. This vehicle. Due to having another child amd dont have the money to take it to a shop. My questio is can the misfire on #3 be causing this bad of a vibration/ shudder? Or could it be low of differential oil? As I have heard it being low of oil may cause a shudder. Havent checked differential oil bc bolt is stripped and will have to possibly weld extention to it so I can remove it. The trans seems. To change out just fine, it picks up perfectly, runs smooth except a little at take off(around 5-10mph) and around the 40-55 mph. Cranks fine and everthing else. Have also noticed a little rough idle in drive while stopped but nothing real major. And have also turned overdrive off and still does the vibratio/ shudder at same speed levels. Thanks! Any help is much appreciated. As we cant afford to replace anything major which is why we traded for the expedition anyways. We figured it was a decent car and more room. It was a decent car for about 5 days, after that we dont know. Whats going on

I have a 1997 ford expedition that I bought about a month ago. Today while driving it it's starts sputtering and kinda feels like it misfires. A friend hooked a device to it and said something about the 02 censor and heater core. What doeas that mean? It is easy to fix? What can I do to fix it?