1996 tacoma 2.7 4X4,no power? engine problems?

hi,
i recently bought a very used 1996 2.7L 4X4
the engine does not seem to turn over much power at all. ppl have said you arent used to a 4 cyl, so i tested that theory and went to a used lot and drove a 1994 toyo 4x4 with smaller engine, it would blow the doors off mine.
so i took mine to garage, they said it probly just needs a tune up,
after replacing fuel,air,oil filters, new plugs, wires, cap, rotor, belts.
nothing has changed. it seems to really lag hard. there is no way it would be able to tow anything. one guy at the garage said the timing chain may be the problem, one guy said it might be low on cylinder compression. I dont know but all that cost me 300.00 ? and it has been through several tanks of fuel already and lucas injector cleaner one time. it is avg 21 mpg, but then again it is not making any power. it feels like when you shift into 3 gear there is no more power. when i took it off road it had difficulty pulling hills due to the fact the engine could not rev up much over 2,000 rpm's to turn over more power. I don't know what the problem is. if the engine was bad would it run so well otherwise. no rough idle or mis or backfire. no use of oil or smoke. It does have 190,000 miles but truck is in good condition. I have checked into other engines just in case, whew they are expensive. I would appreciate any help. i love the truck and want to keep it, i just want it to run the way it should. i will come back to site tomorrrow to see your suggestions. By the way the mechanic that worked on it offered to buy it off of me. Makes me wonder, but it had the problem when i took it to him. I guess he thinks i will give up and he can buy cheap and fix it right for himself, good strategy, i am not going back there. but dealership garages are too costly.

 

I had a similar problem were my truck would seem to be without power or want to turn off unless i gave it gas. I took it to a shop and they had it for 2 days and after checking everything they finally told me that the catalytic converters guts had broken down and got blown into my muffler causing it to become very clogged. after replacing both it ran with a renewed energy. might be that. just sharing the experience.

Krypton

 

i had the same issue i was driving up a hill and was in third gear and couldnt get past 35 miles per hour speed limit was 40 and found broken catalyst jammd against my o2 sensor

 

have a shop check back pressure at the exhaust could be the converter is coming apart and restricting the exhaust or un hook the converter if its not welded and drive it if you feel increased power thats your problem , usually the timing chains dont give any issues they seem to run over 200 k without any problem no point replacing the muffler if its not rusted badly, this is the quickest way to find out campoman sorry didnt notice the date on this post hopefully its running great by now by the way i have a 95 tacoma 4x4 has been great truck until now my computer went bad if by chance you have any leads on a computer please let me know part no.8966104070 thank you