Dodge Repair: 01 Ram 1500: starting/rough running engine

Question
I have a 2001 Dodge Ram Quadcab 1500, and I have been having problems with my truck jerking and popping as I drive down the road, but the popping is constant, even when its just idling.  When its idling, you can smell gas coming from under the hood, also when its shut off, you can still smell the gas.  The popping and jerking as I go down the road started right after I changed the transmission.   Also, I had recently changed the starter, and it quit on me a couple times after I changed it.  So I bought another starter, and it wont even start.  I have a brand new battery, and we even tried boosting it, it wont even take a boost.  I don't want to get rid of it, I just want to get it fixed, since Its going on 16 years since I have had this truck, I bought it brand new before 2001.  Please help.

Answer
Hi Jay,
Lets take one problem at a time, by first getting the starter motor to fire up.
In the power distribution box under the hood there is a starter motor relay. First see whether when a helper tries the starter with the key does that relay make a soft clicking sound, and if it does, do you hear a louder click at the starter motor itself which would be the solenoid switch being also activated. If you do get both of those clicks then check the fat red wire that goes to the starter motor directly from the battery as it could be corroded at one end or the other or loose. But not touch it with a metal tool until you remove the ground wire from the battery (and from the other auxiliary battery if you have one) so that there is no voltage on the wire which could cause a short and burn you.
If you get a soft click from the relay but not the louder click then either the brown wire from the relay to the starter solenoid switch is not connected or the starter solenoid is defective and you need to exchange out the starter.
If the relay doesn't click at all, then check fuse 9 in that same box and if that is OK, then the problem is with the start/neutral safety switch or its wiring or possibly the ignition switch has poor contact inside of it for the 'Start' function. Do you have a voltmeter or neon 12v test light to check for voltage on this circuitry? I can tell you where to test for voltage then.
As to the engine, there sounds like you have a gasoline leak somewhere along the lines from the fuel tank to the fuel injector distribution rail tubing or at an injector itself. Look carefully along all that to try and locate a leak.
Also, try the self-diagnostic capability of the engine control module using the ignition key: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window of the cluster to see if the mileage reading is replaced by a 4-digit number(s) preceded by a P. Let me know what that number is and also tell me which size engine (L) you have.