Check Engine Light - Problems!!

I have a '94 F150, 168,000 miles on it. Recently, after about 20 miles of driving, check engine light comes on, truck loses power, spits and sputters. Trouble code indicates Throttle Position Sensor and Map Sensor. My question is, why does this only happen after 20 miles or so, and which sensor would you change first?? Thanks in advance for any replies.

I have a '94 F150, 168,000 miles on it. Recently, after about 20 miles of driving, check engine light comes on, truck loses power, spits and sputters. Trouble code indicates Throttle Position Sensor and Map Sensor. My question is, why does this only happen after 20 miles or so, and which sensor would you change first?? Thanks in advance for any replies.
I have seen this before on older modles. You end up having to replace both sensors. I am not sure why the engineers made it like. It happens after 20 miles or so because it might be engine temp causing the sensors to act up or an electrical buildup. Make sure when you replace them you reset the computer or just unhook the battery so that the computer resets and the trouble codes are cleared.