1998 Dodge Truck Sudden Sluggishness

I have a Dodge 1500 w/318. It was running great up until 2 weeks ago. Drove it to work one day(ran great) and went to go to lunch and this is when it started. I depressed the gas pedal as normal but I heard a deep sound (like if you were to turn the old style air filter lid upside down) and the truck seemed to not have any power. As long as my foot was "on the gas" the transmission would not shift into 2nd gear - and 3rd and 4th. But if I let up, it would shift to the next gear. Also, if I kept my foot on the gas and even though it would not shift into the next gear, the engine would not turn more than 3000 rpms mo matter what gear I was in. It takes about 300 to 400 yards just to get it up to 35 mph. I took it to a auto parts store and had them check the code as the engine light came on when this first started and they got that it was a random misfire and needed a tuneup. So I purchased new plugs and a new coil but there was no change in the problem. Not sure if this is related but when this started a couple weeks ago, my A/C compressor would shut off after it ran for about ten minutes. The A/C issue is more likely to do this in the afternoon when it is really hot outside but not so much in the morning or evening hours. I live in Houston so it gets real hot here (98-105). I did buy a new relay for the compressor but it didn't help.

Any help with either of these issue would be appreciated as I'm on a really tight budget and really can't afford to take it anywhere right now so the more I could do myself, the better.

Thank you in advance for your help. As far as a donation goes I will gladly give a larger donation if they might know what can be wrong because I have explained this to several certified mechanics and non were right.