PLEASE HELP: Truck Hardly Running, 96 ranger

I have a 96 Ranger XLT. The Truck Starts right up, but as soon as i start driving, it idols like it's missing. It feels like it is running off 2 cylinders. Once it is up to operating tempature it drives normal. every Mechanic i take it to just wants to throw parts at it until it is running right. Can anyone help.

I have an aftermarket exhaust but that is about it.

Is your CEL on? Did it just start this all of a sudden? How old are plugs & wires? You could check for vacuum leaks, clean MAF & trottlebody for cheap fix. Good Luck!

No the CEL never came on, and it did happen over night but it wasn't as bad as it is now. I just had the pulgs and wires changed and another mechanic has looked at it sence then and said they where all gaped right, and looked for a vacuum leak and couldn't find one. I have put a fuel additive cleaner in but i guess i will have to pull off the intake and clean the trottlebody. Thanks for your help

if it only does it when its cold it could be the temp sensor. it tells the computer when it registers a cold reading to send more fuel to motor.if its bad it will not idle up like a choke would