89Hatchback_2.3

Alright so I don't know what is wrong with my 89 mustang 2.3 EFI N/A.

About a month ago I was driving on the highway(about 70-80mph) and my car just started making a loud popping like noise from the engine any time I pushed the throttle.. The more I push, the the louder and faster the popping noise would get.. About a 1/2 mile after it started making the noise my car died(about 50-60mph), It started right back up(still 50-60mph)..

Here is stuff i know,
1) It is not the MAP Sensor
2) My car came stock with a MAF, the guy before me put a homemade CAI on and there is not a MAF sensor or a connector for it on the tubing he used(O'Reilley's Tubing)
3) I replaced the spark plugs less than 6k miles ago and the plugs out of cylinders 2 and 4 are completely fouled, the plugs from 1 and 3 seem to have normal wear.
4) Cylinder 4 which had one of the bad plugs is not firing at all.

I can still start and drive it but when I start it it does not want to start at first.. Could not having the mass air flow sensor cause this to happen?

If not what would be your guesses on possible problems?

SKAR

Id want to check the timing belt. Does it run smoothly well cruising or change throughout the rpm range? How loud is the popping?