Ok pretty new to this so here it goes.....I have a 94 f150 xlt 5.8 ....drove just fine till yesterday...drove home from work parked it for 20 or so minutes....had to run to town..an stopped at the stop sign ..press pr the gas and it falls on it's face....engine rebved an truck takes off just fine.....as I'm driving had to push the gas to the floor and truck barely moved......get to store an it dies at stop light.......go in store truck drives fine home.....next morning drive to friend's house no problem....stay a few hours leave an it shifts hard in 1st an 2nd .....stop at stop light an truck drives just fine....park truck for 4 hrs....start up an shifts hard in 1st an 2nd again....stop at stop sign an have no shifting issue after that

 

Check the EEC for codes.

 

Called to get an OBD1 tester an rep at auto parts store said it would not do any good if check engine light is not on

 

If the OD OFF light ever flashed, there's a code.

 

Never seen that happen ..but I will keep an eye on it

 

Bought code reader today an only 3 codes came up ...10 ,111,128....

 

10 is not a valid code. 111 is ok. However:

128 (M) MAP vacuum has not been changing - check vacuum lines

A bad MAP can make it run bad.

Transmission codes are in the 600's.

 

So now I'm confused....truck ran great today shifted properly....guess the test will be when I drive home from work in 110 degrees

 

http://www.thorssell.net/hbook/3digit.html

Note that you need to do both a key on engine off and a key on engine running test.