I had this idea about mixing altrnate and economy picking, using alternate fir the low strings and economy on the high strings. Since I never learnt alternate picking, I'm not really sure how much it would improve my attack. The low strings sound very muddy. But I havent been able to figure out any other solution to this problem. However, using thee bridge pickup for the low strings make it much better, but still very muddy compared to the high strings, that are very clean.

Any thoughts?

Mixing alternate and economy is been done all the time...Look Malmsteen for example when ascending he is economy picking and when descending alternating or a combo of both(i pick the same way).In your case though its not economy picking that makes the low strings sound muddy but your technique...and the key point in economy is when you cross strings(if you dont cross strings you are alternating anyway).When you cross strings you sweep,one motion to get two notes sounding...make that motion smooth and control your hand when doing it so its not rushed and you are well on your way.Its also a good idea your pick to not have a beveled tip but a pointy one so you ll have much better attack and not dull and muddy.

More important than the chosen technique in this case are other factors like.....tension,economy of motion,aim, not a tight grip on the pick etc etc etc.....if you fail to adress these things the alternate or economy you ll sound sloppy.Practise mostly clean or unplugged for this stuff though..only then you ll know how good or bad you really are....cheers .