I swapped my 2.5 for another 2.5 out of the same year car 86 due to very very low oil presser well this new motor just not working out like my last one did. Here my symptoms with no check engine light

1 Poor mpg 21 to 22 mpg last one was low to mid 30s
2 No power compared to the last one going up hills have to drop a gear or two while doing 65
3 Stumbles when cold hard to drive till its at normal operating temp

The stuff I replaced
All gaskets
Fuel filter
Plugs
Wires
02 sensor
Air cleaner
Temp sensor
New water pump
New alternator

I am planning on picking up an engine compression gauge (should have checked it before swap) but is there something else I should be looking at

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this is the pics of all my cars http://www.motortopia.com/93xr7merc and http://www.fquick.com/bkcamaro
70 Buick Riviera Stage 1 455 Big Block Auto Dual Carb
73 Buick Riviera GS 455 Big Block auto (#2 on dream car list)
78 Chevy C 10 Step Side Pick up 350 auto
85 Chevy Camaro Z28 383 stroker auto (#3 on dream car list)
96 Chevy Camaro Z28 350 LT1 auto (daily driver during the nice months) 14.1 at 99.25 mph 8/5/09
98 GMC 2500 350 auto (plow truck)
86 Pontiac Fiero 2.5L 5 speed (mgp car)
Videos of most of my cars http://www.youtube.com/user...eos?flow=grid&view=0

Still have the old motor?

Could be a clogged catalytic converter ?

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check engine light on?

Did you swap the TBI?

quote Originally posted by Gall757: Still have the old motor?

Yes I do

quote Originally posted by Firefighter: Could be a clogged catalytic converter ?

There is no catalytic converter car never had one since I owned it

quote Originally posted by jaskispyder: check engine light on? Did you swap the TBI?

No check engine light and the bulb is good

I took everything off my old motor and put it on this one since I knew everything worked

If the timing is retarded, then it will be down on power and economy.

quote Originally posted by fieroguru: If the timing is retarded, then it will be down on power and economy.

never thought of that mmmm that makes since

do you have a 195 T-Stat in it. Is the little deverter plate under the T body still their?

quote Originally posted by FFIEROFRED: do you have a 195 T-Stat in it. Is the little deverter plate under the T body still their?

yea i a running a 195 t-stat in the winter when its hot out i switch them out

deverter plate? any pics