Replaced lift pump with factory 3-4 years ago, threw codes again (1689,1693) about a month ago or so (after ex drove it for a couple months without it shifting properly), replaced lift pump again with fass ddrp02, then 0230? code came on (lift pump electrical failure). A couple weeks later all codes disappeared, however truck still not shifting properly. Brought it to a shop today and they said bad gasket on tranny and it was leaking fluid. They did a tranny flush on it (replacing gasket) and it was 5 qts low because they didn't heed my advise on checking the dipstick not going by factory suggestion (deep pan). Now with the proper amount of atf fluid in it, its still not shifting properly (though, admittedly better). Am worried it may be tranny or electrical, though friend says probably torque converter. Not as concerned that its the vp44 because codes have disappeared. Also curious if it could be tps or apps? What should I be doing next to help with the process of elimination and try to get my truck back on the road while saving some cash

 

If it's not shifting properly, may be shift solenoids on the valve body, could be valve body, or could be tranny and tq converter... Start small then go big