Most likely the problem is a bad (weak) igniter. If you would like to measure the current drawn by the igniter, you should wire an amp meter in series with the igniter and set it on 0-20 amps scale. You also can use a clamp on amp meter which does not need to be wired in but such meter is much more expensive.
I would just order the new igniter and install it to see if it will fix the problem. If not, you can return it (only if it's ordered from Appliance Parts Pros).
- The oven igniter
Part number: AP4096256 
Here are the breakdown diagrams and
Replacement parts for MAYTAG MGR5780BDW Range - S/c F/s Gas | AppliancePartsPros.com
Gene.