I have a 1986 RV with a ford econoline 350 front end. Had power when we first drove it but had several problems with fuel boiling and shutting down the engine. After 4 trips to a mechanic we finally got the fuel problem resolved (new fuel pump and new muffler). Now it has no power. Have to shift to D2 for any small incline, esp. freeway onramps, D1 for major hills. Takes forever to get up to 55 unless we're going downhill. Any suggestions? On a side note, the A/C which we just had fixed a two months ago is no longer giving us cold air, possible connection?

Thanks!!