can a loose battery cause a car not to start? Options

[homebuilder]

Hi,

My car every once in a while will not start. The starter turns over but it does not catch. Then if I wait a while it will work.

A mechanic looked at it when it did this once, he went under the hood saw my battery was not tied down properly, he moved it over hit the top of the cable and it started. Now I do not know if it was him moving the battery or just the normal, wait a minute and it works.

So anyone else have this problem? Anyone think it is the battery?

I plan to secure the battery anyway, but just wondering if that's really the problem.

[homebuilder]

Weird... it happened again twie today. The first time after moving the battery it started right up. Drove home, ten minutes later it again would not start. Tried to not move battery, then moved it, still did nto work. Waited ten more minutes moved battery and it worked... but seems to be sluggish.

I got new spark plugs and I got a fuel pump and filter from a 97 in a junk yard. I wanted to get a new filter, but pep boys was out. I may replace the fuel pump and spark plugs tomorrow, see if that helps.

Any suggestions or warnings on a used fuel pump? used filter?

Curious, can you clean a filter?