'95 Ram, extended cab
5.9 Magnum

My wife managed to blow the head gasket. Had it fixed by the local mechanic. Now, it begins shaking at 45mph until I reach 65. The gas milage is HORRIBLE. I know its big truck, but when I got it it would do 16-18 mpg, now I average about 5-6 mpg.

What the hell did he do to my truck?

 

I did check the mass air sensor, it wasnt even hooked up. I plugged it in and helped a little for the mpg, but nothing else.

And if I turn the overdrive off, the shaking stops.

 

Codes?

flip the ignition on 3 times to the run position and back off real quick 3 times leaving it in run after the 3rd. Then count the groups of engine light blinks. Those are the codes.

 

almost sounds like (just my opinion) your torque converter is going out

 

Or, a miss. Right around 45 mph, the torque converter clutch locks up, and if you have a miss on one or more cylinders, you REALLY feel it then.

Check plug wire routing.