1993 Travelaire 454 chev p30 low power

I would do several things to narrow down this problem. The first thing I would find a flat stretch of Highway and do a 40-60 mpg test and post the time,if your wt is about 15,000 lbs with no mods 20 secs would be about normal and your MH would be normal, you only have 230 HP stock. The second thing is to check your computer and see if you have any stored codes,it should be an OBD1 and the service light will flash what codes are stored. If you search this forum it will give you the details on how to do this with a paper clip. Third, look at the spray pattern of the two jets in the TBI, it should be a nice cone shape with no drips, a flash light helps to see better into the throttle body. I would then check the timing should 4 degrees before TDC. Some have advanced their timing up to 12 degrees before TDC. I advanced mine to 9 and it took 2 secs off my 40- 60 mph time. When you increase the idle speed the timing marks will should advance, mine will advance if I remember correctly to about 22 degrees if it doesn't you found the problem. My distributor is electronic, your 93 may be mechanical and others have already commented on that and the cat. Good luck and let us know what you find.