Barak Momrik

My avalanche since I bought it used, has had a starting problem. It will crank over for a while until it starts up and if it doesn't crank it will sounds like a soft start and then roar up like not enough power was supplied. I replaced the fuel pump and it doesn't seem to be the problem unless it's a electrical part to the pump. Also I have a remote start installed and someone told me it can cause problems. Also the ignition is a bit wiggly. Very hard to figure it out. Any advice? I've been thinking maybe a starter or even spark plugs... I've had the alternator and couls checked with a detector hooked up to my batter but I'm not sure how wel it read. Any ideas?